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'.

Bachmann Spectrum On30 PRR Baggage Car Brand New
Bachmann Spectrum On30 PRR Baggage Car Brand New
$29.99
Time Remaining: 3d 15h 17m
Coca Cola Hawthorne Village Baggage Car
Coca Cola Hawthorne Village Baggage Car
$99.00
Time Remaining: 17d 18h 53m
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: 27d 48m
Buy It Now for only: $89.95

Other On30 Scale train items recently purchased through this site:

Bachmann Spectrum On30 PRR Baggage Car Brand New
Coca Cola Hawthorne Village Baggage Car
On3 On30 WISEMAN SM 101 DRGW OPEN PLATFORM BAGGAGE PASSENGER CAR KIT