Being the cheap guy that I am, most of my trains have been "deals"!
One of my favorite phrases is "new old stock"
Focusing on just engine, the K-Line Collector Club items were great,
- scale size Pennsy A-5 (conventional) for $125
- scale size CSX SD70MAC with sound, speed control and smoke for $150
- scale size Lackawanna Trainmaster with horn and smoke for $125
although, I think an even better price might have been my K-Line scale Pennsy Mikado that I purchased, on blowout, from Trainworld for $219!
or, it could be the SGL Reading Heavy Pacific (all brass) that I bought from Trainz for about $325. This engine may have been test run, but it was originally a $1000 engine.
Jim
p.s. the guys that complain that model trains are an expensive hobby, aren't patient enough to wait for the deals!