hi, walked into the minefield of thinking of getting a projector, couple of points i can not get my head round, and that is nothing new, first, do they connect straight into the laptop, and a bit more important, how can you tell how big the image will be, our room is only about 14ft across, would not like to get one only to find once it was set up that the image at that distance was about the same size as a TV.
I have used various and sundry projectors in the past. And does seem to be very much that you get what you pay for.
Look at the light output of the bulb (should be expressed in 'lumens'. The brighter the better. But... they do cost a lot to replace. One at work blew its bulb and that was £350 to replace!
Look for a zoom lens so that you can make the picture size variable.
If you can run to it, look for one with a remote control (not all projectors have them) to make presentations slicker.
One that has a 'hide screen' ability avoids having to keep switching it on and off (detrimental to bulb life).
Ideally, one that is flatter in profile instead of taller makes it a lot more stable and less prone to being knocked over or 'wobble'.
And whichever you get, make sure that when you switch it off, it does cool down properly (again to prolong bulb life) coz switching it off, unplugging it and bunging it in the case is also pretty tough on the bulb.
Finally, if possible, get to see the one that you like demonstrated! Colour reproduction can end up looking up quite different to what's on your screen. I had a presentation to give where the background template was predominantly yellow; and that tended to come out an infantile pooh colour! Not very flattering! You're spending money, so the vendor should be willing to show. If not, why?