The other thing you might consider is purchasing a Williams PRR brass locomotive from the 90's. They are not as detailed as more modern vendor offerings, but they are inexpensive and easily upgraded to TMCC. And being Williams, they run very, very well.
I recently purchased a Williams PRR B6sb in C-8 (like new) condition for $200. I spent about $300 having TMCC, Railsounds, and cruise (ERR components) installed. It also got front / rear electrocouplers. I had All Aboard Trains in NJ do the work and I am very pleased.
Nearly my entire Pennsy fleet (2 K4s, 1 L1s, 1 B6sb) is Williams brass locomotives with TMCC upgrades. They run great. Below is one of my K4s pacifics.
This is a very economical way to get a brass TMCC locomotive.
George