Projectors are a high-strain electronics item. They have a light bulb in them which runs at a few hundred degrees which is surrounded by electronics. So, a projector that is 5 years old is often at or near complete failure, and likely is due for a replacement lamp which TYPICALLY runs about $300.
There are real considerations which you must address. With a flat panel, you set it on a table and walk away and it's wherever you put it.
With a projector, you setup a screen. Call it a 120" diagonal screen.
Then, the projector must be placed a certain distance from that screen. The lens impacts that distance. It may be 5 feet (rare) it may be 12 feet (more common) it may be 14 feet or more. Each projector is different and they use a different lens, so if you have ANY requirements for a distance which the lens to screen distance must be, then that must be factored in to your purchasing decision.
Also, the projector is most typically mounted right side up several inches below the bottom of the screen, or placed upside down, several inches above the top of the screen. This, once again, is a factor of the lens on the projector. If you need the projector to be placed right side up, near the top edge of the screen, then there are some projectors with a lens design that includes lens shift. Lens shift will allow for the lens to be adjusted up and down properly to suit your needs.
So, okay, after dark, doesn't have to be top shelf.
But, the following questions still need to be asked:
1. How large of a screen are you shooting for? (I would recommend 133 to 150 inches diagonal if you can)
2. Can you place the projector at any distance from this screen?
3. Can you place the projector at any height in relation to the screen?
For audio, I would scour Craigslist for a used A/V receiver and speakers. You can get some decent stuff for next to nothing vs. buying new. Terrible for the most current in surround sound, but great for what your setup is sounding like.
Keep in mind, many of the newest devices do not have analog audio outputs on them (AppleTV, new BD players), so you may need something to convert digital audio to analog.