Don't buy electronics from the Mid Store. It's never a good deal.
Wait until the end of Plebe year. Your firsties will be looking to ditch their TVs (and speakers, projectors, game consoles, all kinds of crap), and your upperclass will be looking to upgrade their stuff.
Definitely don't buy anything until the ac year. Every company's training policy is different. As a plebe, I was authorized one monitor, no larger than 30''.