Hi,
Im in the same position and from reading around i've come up with a list of four different projectors.
Optoma HD600X
Optoma HD66
Optoma HD67
Acer H5360
I was going to go for the Optoma but after a bit of research into comparisons im going to go for the Acer H5360, every comparisn post i've read says its alot better and most of the comparisons i've found have been written by people who have had experience with both. There are even posts saying they took the Optoma back and got the Acer.
The Optoma has less rainbow affect from what i've read but the Acer's colours are alot better.
Having the Acer will cost about £100-£150 more than your budget though depending on what screen you get. The projector is currently £544 at amazon and screens can range from £10 if you use a blackout blind to over £100, these would give a better imgae but cost more. I think the more expensive screens are better for 3d.