My advice would be do not try and go too cheap as you will end up with a new one sooner rather than later.
I did a full room build and did all the work myself. If you have any questions let me know.
I choose a Garmin R50 as my LM as I didn't want to spend too much for an overhead and didn't want to have to go by a PC as well. In addition Garmin doesn't need to have a GSPro or other subscription to work.
I do however connect to GSPro and it need a powerful PC to run it.
I did everything from painting, installing protective padding, overhead lights and projector, changed my garage door to a jackshaft and raised the rails.