Cabinets are the last frontier for do-it-yourselfers. Most cabinets
are sold through design centers that specialize in selling whole
kitchens. The stuff that Home Depot stocks is overpriced junk.

There are a gazillion places that sell stock cabinets over the
internet. Just do a Google search.

Two places that sell ready-to-assemble custom cabinets over the
Internet a
www.scherrs.com
www.maplecraftusa.com

I've ordered cabinets, drawers and doors from Scherr's, and I've been
happy with the quality. But I have to warn you they're not cheap.
And getting cabinets shipped to a residence is expensive and kind of a
pain as you have to use truck freight.

If you are determined not to build them yourself I would look for
someone small and local who supplies contractors. The hard part is
finding such a guy. But you should reconsider building them yourself.
I built some cabinets for my basement workshop, and I would call it
an advanced beginner woodworking project. Basically, if you can cut a
sheet of plywood to accurate dimensions, you can build a cabinet --
it's just a box.

Some other things to keep in mind:
You didn't mention drawers. I found that making drawers was more work
than making the cabinets they go in. I also bought some drawers from
Scherr's and it came to about $90/drawer including assembly, finishing
and shipping.

Unless you have a good source for hardware it is very easy to spend
more on pulls, hinges and slides than on the wood for your cabinets.
This is the biggest pitfall of building cabinets yourself. If you buy
carcasses, try to buy hardware at the same place. The volume
discounts on hardware are substantial.

Nick Keenan