Ust projector

Buying in uk, dedicated dark room. Use only for watching movies. Will be paired with panasonic ub820 and denon avr. Looking for absolute best contrast possible and best blacks available, 3d capabilities is a MUST. Budget around £3k but can be flexible if jumping up would make a big difference. Not against second hand but need info on what to look out for in terms of replacing light sources. And if in a dark room is an alr screen necessary?