Need A Projector For Macbook Pro

I need recommendations for a Mac-compatible projector for use in the classroom. I have a Macbook Pro with OS X El Capitan. My school has a small, cheap projector and they bought the required Mac adaptor as everyone else uses PCs. But when I got it hooked up, all I could get it to do was project my desktop (and poorly, at that). It wouldn't project any of the actual apps I was running -- for example, a YouTube video off Safari. I don't remember the brand but I was told by "the tech guy" that the projector isn't Mac compatible. As it was cheap, I thought it would be better for me to get my own. I've done some looking around and it seems like the projectors recommended for Macs are way out of my price range -- over $1,000. I can't pay over $150.00.

Ideas?