If the cabinets are solid and you can replace the drawer runner and hinges, buying doors and drawers is definitely the way to go. And if you want them painted they do a much nicer and more durable paint job than you can do unless you have a nice setup to spray.
About 15-20 years ago we had a sun room that we converted to a kitchen. So we basically had to do everything from replacing some floor joists, reframing the walls, building a bay window, all the way to cabinets. We hired out the plumbing, drywall, electrical, and tile. When it came to deciding between building or buying cabinets, we decided to build from scratch as the quality we wanted was going to be way too much $$. I ended buying most of the required tools - table saw, jointer, planer, router, etc. and still saved so much money that we could buy a Wolff range and high end exhaust fan and still came out ahead.
I think it took over a year when all was said and done. But they are still the nicest cabinets I have ever seen in a kitchen. We're trying to move into or build a new house and I am going to miss my kitchen. If we build, I doubt that I will be willing to pay for the same quality and I am certainly not going to take on a project like that again.
