We've searched the internet and found the largest collection of On30 Scale trains for sale is on eBay. Below are the listings for 'baggage car'.

Coca Cola Hawthorne Village Baggage Car
Coca Cola Hawthorne Village Baggage Car
$99.00
Time Remaining: 12d 17h 48m
Buy It Now for only: $99.00
On3 On30 WISEMAN SM 101 DRGW OPEN PLATFORM BAGGAGE PASSENGER CAR KIT
On3 On30 WISEMAN SM 101 DRGW OPEN PLATFORM BAGGAGE PASSENGER CAR KIT
$89.95
Time Remaining: 22d 23h 43m
Buy It Now for only: $89.95

Other On30 Scale train items recently purchased through this site:

On3 On30 WISEMAN SM 101 DRGW OPEN PLATFORM BAGGAGE PASSENGER CAR KIT
Coca Cola Hawthorne Village Baggage Car