Careful with removing the CRT. The stuff inside it is toxic if I remember right and you have to get it removed specially. Although chucking it in the normal bin works just as well
Also if you're spending $250 usd, you're paying way too much forr one. Or getting a pretty high end one.
As a guess without know exactly the space requirements, a 21"-24" LCD should be good. If you want to go the fancy way you could get a card for the
PC to allow it to hook up to TV and use that as a screen.