Obviously if you buy used there won't be anything like as significant a loss in value as buying new. I agree that CD players don't become collectors' pieces (and hence appreciate in value) except for the very first original Sony, for its curiosity value (certainly not its sonics).
Besides the consideration of $$ it depends on what else you're trying to achieve. The Sony 5400?? Bryston BCD-1's (the original model) years later still command a reasonable price. Logical to think the BCD-3's may do too.