Check Consumer Reports. They just did a review recently. I don't rememeber the exact month or the cabinet makers mentioned, but the article did reference what makes a difference and constitutes good quality. Good Luck!

Have you searched the Kitchen forum yet? There's an absolute wealth of information on that board -- several KDs, planners, and tons of folks who've researched their cabinets for their own renovations.

Two recent threads immediately came to mind:
Relative cabinetry prices: brand vs. brand
and
those doing ikea kitchens

HTH

Don't forget, these are really just boxes with doors. The branding and advertising will drive the prices far beyond the differences in quality of materials or construction.

Maybe this one? (I haven't perused it yet.)

Here is a link that might be useful: kitchen cab reviews