Our school has ditched projectors in favor of mounted TV's in every classroom. Yep! Every single classroom has a TV paired with an AppleTV (and some also have Chromecasts). The picture and sound quality is MUCH better. The cost is much more affordable too! We were able to do the entire package of TV, mount, and streaming device for around $500! The TCL TV's now come with AirPlay built-in!
Here's what we bought...
Note: Look for education pricing on the AppleTV. Also note that the mount comes with a good HDMI cable, freeing you up from having to buy one. Optionally, you may wish to add or substitute a Chromecast. You can get them at almost any major retailer or online for $35.