I also agree, The Sets (I got the Imperial RailKing Big Boy Freight set) are an awesome deal.
The cars sell for over $40 each, you get 4 (with unique road #s) plus a caboose worth over $40. That's $200+ in cars for $100 over engine price. And the engine is identical except Cab number to the standalone sell engines. This set also came with no track or Transformer. IF I recall Correctly, for MTH only he starter sets come with those items. And those do not have Imperial engines by a long stretch. Closer to Rugged Rails, IE no frills but good runners.
Any of these are a good deal and Especially helpful if you are just getting started as I was.
I now have nearly a dozen of those reefers in that consist and a woodside caboose that better matches the engine's timeframe, but still have that original caboose on the layout.
That engine will pull everything I can fit on the layout main loop (current max 58 cars) without even noticing.