Cheapest way to replace baseboard heat covers?

My three-family house was equipped almost 30 years ago with American Standard (now out of business) baseboard heat. The baseboard covers are old, dirty, rusty, falling apart, and sometimes missing pieces, especially in my tenants' apartments. They're a real eyesore, but the heat still works, and I'd like to get new covers, endpieces, etc. to make the tenants' units look more cosmetically attractive, since I'm doing the places over (painting, new sanded floors, etc.) and looking to raise the rents for new clients.

Can my plumber replace the covers using "dummy" baseboard units or in some other way that isn't going to break the bank?

Please don't even bother suggesting Overboards or the even more ridiculously priced Radiant Wraps.

Help!!!