We just put board and batten up in the dining room (and one wall in the kitchen). Total cost was less than $100 (for mdf, trim, primer, paint, and a mitre kit we'll use again) and I think it really fits our 1905 farm house. It really kicks things up a notch for the cost, IMO.
Husband and I put up in about 5 half days (with a 2 yr old this was better than full days). We have no experience with really anything similar and I'd say it wasn't hard (just followed the steps in this blog
http://theturquoisehome.com/2013/04/how-to-install-board-and-batten/ ), but it was tedious.
Next on our list is redoing our kitchen counters ourselves (taking down mini backsplash, painting and sealing the counters using a resin, repainting walls). I'm thinking we can probably do that for about $250.
Any previous or planned home projects that are aesthetic but high bang for the buck?