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

HOn3 Silver Princess brass DRGW caboose in original box
HOn3 Silver Princess brass DRGW caboose in original box
$85.00
Time Remaining: 12h 52m
Buy It Now for only: $85.00
Bachmann On30 Scale Train Caboose Off Set Cupola Caboose White Pass Yukon 26564
Bachmann On30 Scale Train Caboose Off Set Cupola Caboose White Pass Yukon 26564
$54.19
Time Remaining: 5d 6h 43m
Buy It Now for only: $54.19
Bachmann On30 Scale Train Caboose Off Set Cupola Durango  Silverton 26565
Bachmann On30 Scale Train Caboose Off Set Cupola Durango Silverton 26565
$54.19
Time Remaining: 5d 6h 43m
Buy It Now for only: $54.19
On30 Custom Caboose
On30 Custom Caboose
$75.00
Time Remaining: 6d 2h 33m
Buy It Now for only: $75.00
SN3 4 TOMALCO DRGW LONG CABOOSE W TRUCKS COUPLERS BRAKE DETAIL AND DECALS
SN3 4 TOMALCO DRGW LONG CABOOSE W TRUCKS COUPLERS BRAKE DETAIL AND DECALS
$39.00
Time Remaining: 20d 9h 43m
Buy It Now for only: $39.00
Bachmann On30 Scale Train Caboose Painted w round Roof  Lighted interior
Bachmann On30 Scale Train Caboose Painted w round Roof Lighted interior
$59.00
Time Remaining: 26d 8m
Buy It Now for only: $59.00

Other On30 Scale train items recently purchased through this site:

On30 Custom Caboose
HOn3 Silver Princess brass DRGW caboose in original box
SN3 4 TOMALCO DRGW LONG CABOOSE W TRUCKS COUPLERS BRAKE DETAIL AND DECALS
Bachmann On30 Scale Train Caboose Painted w round Roof Lighted interior
Bachmann On30 Scale Train Caboose Off Set Cupola Durango Silverton 26565
Bachmann On30 Scale Train Caboose Off Set Cupola Caboose White Pass Yukon 26564