... There a bit hard to find. You may luck out and find standard cabinets being sold in a custom 'shop'. You'll just have to ask. Also, stores like IKEA may sell them. Be forewarned, not all kitches in the home were built in a 'standard way'. BUT, once you take your measurements and some pictures w/you to the store/shop, you'll have a better idea if what you want to do will work.
Also, about Salesmen, switch places w/one for a moment. Hypothetically speaking, suppose a cabinet maker also did 'sales'. If he spent all his time 'selling', he wouldn't have any time making cabinets. So, as part of the 'cost' of doing business, he has to charge his customer some 'fee' for spending time w/them to design their cabinets. This is even w/standard cabinets. I'm sure you're going to have questions. The 'fee' he/she may charge you is built into the cost of making the cabinets. Believe me, that's done too w/off the shelf cabinets unless you could find them at a garage sale. (And at times you do ...)
Here are a couple of links that handle standard cabinets. Benchmark and Wood-O-Rama. One is in NY, the other is in NJ. You might want to ask around at job sites or at other cabinet makers for other leads. And don't forget the Amish if they're near you. They do fine work, IMO.