Not including any provision for a boxcab, I counted 11 "sets" (single, or sets of locos).
If the A-B-A and A-B listings are separated, it's 12 + boxcab, and 2 dummy B units.
He only lists 11 in the description, including the boxcab...
I was really starting to wonder about the total, as well.
A quick tally in a word processor gives me 321 items. Removing the locomotives gives 309 pieces of rolling stock. If you figure an average of $16 each, the total value is about $4944. If you give the locos an average of, say, $130 each, it's $1560; or $1200 @ $100/ea.
Combined, you've got $6144 to $6504 for a really rough estimate of used pricing. (Not including the rolling stock sets. I'm not going to take the time to count all that crap.)
$6,999 might be reasonable, but I don't know that he'll have any takers.