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
$80.00
Time Remaining: 1d 2h 45m
Buy It Now for only: $80.00
Busch 32000 Tt Gauge Luggage Car Pwi 93  New Original Packaging
Busch 32000 Tt Gauge Luggage Car Pwi 93 New Original Packaging
$39.77
Time Remaining: 2d 11h 50m
Buy It Now for only: $39.77
Railway Post Office Baggage Car Tokaido Sanyo 6 Car Set Model Train by
Railway Post Office Baggage Car Tokaido Sanyo 6 Car Set Model Train by
$269.36
Time Remaining: 4d 9h 40m
Buy It Now for only: $269.36

Other On30 Scale train items recently purchased through this site:

Coca Cola Hawthorne Village Baggage Car
Railway Post Office Baggage Car Tokaido Sanyo 6 Car Set Model Train by
Busch 32000 Tt Gauge Luggage Car Pwi 93 New Original Packaging