I would start the project by doing a Google image search for “kitchen pantry cabinet”. There are all sorts of designs and useful gimmicks that you may decide to integrate into a rough sketch, with dimensions, of what you want.
And truthfully, you will almost always be more satisfied with a custom job, using quality materials.
My own suggestions may seem odd, but make a lot of sense. First of all, assuming the cabinet is recessed into a wall, it might be a very good idea that the outer walls of the pantry are insulated. Thus your pantry will be room temperature, summer and winter.
Second, if you have lots of insects, you might consider having small valves on the top of the pantry through which you can spray insecticide every few years. Having to remove your pantry to spray for ants is a nuisance.
Other than shelf drawers, you might have a wine rack, lazy susans, various space saving square sealed bins for grains, pasta, etc. And be sure to line your shelves with shelf paper.
If you do find a used piece of furniture. I’ve heard this stuff works great for refinishing:
http://www.anniesloan.com/acatalog/copy_of_How_to_use_the_paint.html
Just go to Lowe’s and look in there cabinet dept. Tell the salesman what you want. They have many qualities to chose from and they come pre-finished. Delivered to your door in about 3 or 4 weeks. You install or pay them to install.