It shouldn't be difficult to find a standard size door that can be trimmed to those dimensions. Where have you looked?

You need to go to a real lumberyard, Should be no issues at all with having a stock door modified. You do need to know if the door is 1 3/8" or 1 3/4" thick but typically closet doors would be 1 3/8".

A standard door size would be 24"x80", so you should be able to get a door trimmed to the size you need. A good handyman with a table saw should be able to do the work. A solid door would definitely have the "meat" needed to take the trimming, and you can check the specs for the hollow core to see what it allows for.

I think it would be pricey to have it done at a lumberyard. Most lumberyards have transitioned to a more traditional sales model where its either in stock or requires a special order. They would probably have to send the door out to have the work done.

Bruce

Thank you all for your responses. Much appreciated!