The darker the room, the more important a good projector becomes. The best projector around $2,500 right now is the JVC HD250, next up is the Epson 8700UB, then the 8350 is what I would recommend.
Most people say the same as you 'The room would be completely dark with no lights on' - but then they have light walls, a white ceiling, and light carpet. In that room you will NEVER have it completely dark when you have a giant flashlight of a projector lighting the room up. It's worth knowing this, because if the room is not truly dark, like dark walls, dark ceiling, and dark carpet, then you may miss out on quality and then it makes less sense to get a better projector.
The 8350 is a great entry level model and paired with a decent Carada screen is a solution which should last you for years of happiness.