"Yes, really.
(numbers for example purposes only):
I can race an ITA car in ITB that will cost me $2500 or I can race an actual ITB car that will cost me $3000 to build the engine. What do you think will happen to the price of that ITB car?"

Cost to built it? Or value if you sell? Unless you can take the stock engine option, nothing different to build it. If you are looking at the car as an investment, very little (as always), although if the stock engine option exists, it would be easy to sell with a handgrenaded motor!

"Now, you can class that ITB car without the IT-engine prep down into ITC (so that when the race motor craps out, he can slap a junkyard motor into the car and be competitive [EDIT-with addt'l weight!]), but what are you going to do about the ITC guys (not that there are many left...)? And, doesn't that defeat the purpose of having larger fields in each class?"

Not really. This way of classifying newer cars into B & C should make building a car MUCH cheaper and encourage new blood. How many would join us if there was a much cheaper option to build a competitive race car in B&C? Do the majority of the B&C entrants expect to cash in their car for a large amount of money? NO! Only the minority who are pushing this envelope to the max with uber-builds and trailer queens. Sorry if I seem condescending, but let them eat cake! Racecars were never a good investment. A problem in B & C is the graying of the cars that exist-the majority are pretty old and used-up. This might revitalize the gene-pool if people with tired A1s. A2s, 142Es, etc saw an economical way to jump ship and stop hoarding extinct parts. As far as the possibility of moving a B car into C: if I were one of the few ITC guys left, I would be so happy to see them coming!