That depends. Your are correct in your point though. I am no expert (ask Sushi may be in order again) but based on my research well..the higher the price will buy you more resolution...sometimes the resolution is 4:3 sometimes its 16:9. 16:9 projectors tends be more more expensive but all 4:3(current ones at least) can do 16:9. Having a 16:9 projector could be better only because the 4:3 doesnt have to be rescaled to 16:9.
Having more lumens yes does cost more money but doesnt equate to better quality. It does equate to better pictures in ambient lighting. But movies are best in the dark so lumen output is not a critical factor. Actually high lumen output over saturates whites level and black levels are not black. For example PQ(picture quality)improves on the Panny model above when set to cinema mode...turns down lumen output.
Another thing to note...there is LCD and DLP projectors. I personally can't stand "chicken wire" or "grids" which can be prevalent in lower end LCD projectors. The Panasonic LCD PJ does a great job and apply certain filters/technology to get rid of those "chicken wire". While DLP even in the lower end has very very tiny "chicken wire".
DLP projectors use a spinning color wheel. Lower end PJ have 2 time color wheels. The higher model have 5 time color wheel. The faster the color wheel the less likely to see so called "rainbows" which does affect a small part of the population. So again someone may opt for a LCD projector because they are sensitive to the "rainbowing" on DLP projectors. But that disappears in time as your eyes gets used to it... as one gets use to the ummm met%$#%c or brig#* sound of Axioms.
Well for $900 USD you can get a X1 and project a 80-110 picture or a 32 inch Sony Wega CRT. Thats how I equated it at the time.
The X1 picture is as good or better than projector under $5000 from the last 5 years. The Sanyo Z2 at 1.5 times the cost is close in quality to the X1. The Panny a little better than the both but is 2.5 times the X1 and give a nicer cleaner 16:9 picture even in sitting position less than 10 feet. I would put any of these 3 budget PJ to quality up to about $5000.