I have read through your original question and subsequent comments with disc and myself.
I hope you haven't rushed out a started to purchase bits and pieces.
I have no connection with any of the sites or products I mention below but I have used their knowledge base to make my decision on my new setup(s).
As someone who is old enough to be your Great Grandfather I cannot stress enough you need to do your research before you embark on your financial outlay considering you have a budget limit.
With your now current proposal that research is necessary.
Did you try to make contact during Independence Day celebrations? Don't give up on trying to contact Michael Brown. If you go to the following link you will find a phone number (if you are in the USA) and also have a look at his minimum flight sim package. The link is found at https://xforcepc.com/english/platinum-html.html Scroll down the page and you will find the specifications for this unit and also take the time to watch the video produced by MIchael further down the page. Consider the messages he gives on what components to use.
My system is in the process of being rebuilt and is based on a high end PC to run my aircraft out of cockpit view with three 43inch FHD televisions connected to the GTX1080 graphics card. Although I do have the saitek switch panel it will be used and I also have the saitek radio panels (2 units and saitek yoke and two throttles. This unit will run X-Plane. I also have another high spec (at the time of purchase/build) PC that will be linked (networked) with the other PC to run AirManager for the purpose of showing my aircraft instruments. Attached will be a 24 inch touch monitor. The whole system is built around the work done by Russ Barlow's videos. The link is provided below.
With regard to the displays consider using FHD televisions. They will work provided the TVs have HDMI connections and your graphics card has at least 3 HDMI ports along with a display port (4 connections in total). This may allow you to use 3 screens of the same size. This is also emphasised in the videos by Russ Barlow and Michael Brown.
The proposed monitor stand will not give you the 45 degree angle viewing. You may need to use table of sufficient size to stand your screens on giving you the ability to set them up at 45 degrees to each other. Russ also goes into setting up your screens.
In regard to the Saitek switch panel (which I have) and you chose to use it, as soon as you open the box dig a large hole in your back yard and bury the software. The same applies for any other Saitek/Logitech units whether they are instruments or hardware items. There is no other way. For the switch panel you need to download the following software found at https://forums.x-plane.org/index.php?/files/file/14646-xsaitekpanels-linwinmac3264/ the software is written by Sparker who is an experienced and long time user of X-Plane. Others may tell you differently. Don't waste your time on downloading saitek software updates.
In relation to your flight controls I have only the Thrusmaster joystick. It will be installed when I cross over to helicopters. I will most likely have to purchase the throttle component. All hardware has to be configured through X-Plane. The throttle and joystich have to be configured independently No other way. The advantage with recent updates is you can configure the joystick and or throttle for individual aircraft then save for that aircraft whereas before when you fly a different aircraft you had to reconfigure at the time of wanting to run X-Plane.
In relation to Airmanager I will be using my 24 inch touch monitor for most of my planned use aircraft. If and when I chose to fly the C130 Hercules I will most likely use what is now my obsolete 27 inch monitor just to fit the simulated instruments. Airmanager is now the package to use over and above a package called Panel Builder (PB) from Simplugins. I have an older version of PB but not installed.
Airmanager is not free. The purchase site can be found at https://www.siminnovations.com/buy/product/36-air-manager-v3 Spend some time in giving the site a thorough search. A lot of information. If you have any queries send Ralph an email. Ralph is only too pleased to help out. I have even phoned for assistance despite a 8 hour time lag difference with the Netherlands and downunder. SimInnovations now market the "knobster", a switching control used with airmanager and the touch screen. It was developed by Russ Barlow. Not only are predefined instrument panels made available with the software but customised panels are also available at additional cost
This site may be of some help as well found at https://forums.x-plane.org/index.php?/forums/forum/202-air-manager-panel-development/ I have not trawelled through the comments. What I suspect where comments have been made by LNRalph it is from Ralph at Siminnovations.
Now regarding Russ Barlow. The link to his video site can be found at https://www.youtube.com/user/srbarlow/videos Take your time in viewing all these links if you want to understand what airmanager is about. I cannot stress this enough. Russ is one of the developers of AirManager. He is located in the USA. I became interested in this site as he was working on the development of version 3.0 when the official release of Airmanager remained in 2.8 (?) There is a lot of "good" information provided by him. Russ was also involved with the "knobster" now market by Siminnovations. There are a few videos that are not relevant.
Russ also discusses setting up your main screens (4 videos) including where you need to sit for best benefit. He also has a lot of discussion on the use of the touch screen and particularly any loss of frame rates.
I have used Russ' videos to purchase and plan the setup for my new arrangement. If you have some queries make contact with him. I have a few time and he is quite helpful.
Now I also stress again in having a "good" look at the videos from Michael Brown. Take your time. Either take notes or bookmark the video for reference at a later date I have already given you a link regarding the building of a PC. Consider the message he provides about components. Consider the reference about using a SSD drive versus a hard drive unit. The good thing about building a PC is you can upgrade components as you go. Here is the link again for all of Michael's videos found at https://www.youtube.com/user/col2mab/videos
In these videos Michael discusses using Airmanager in several videos, including frame rate loss, and he has recently produced at least two video on installing the GPS530 unit you plan to use.
I think Russ Barlow discusses the installation of the GPS unit.
Take your time in the planning of your system.
Send me a private message when you have decided on the building of your cockpit.
Good luck and apologies for the long comments.