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

On30 5 Ton Wooden Hopper Car Prairie Locomotive Works NIB
On30 5 Ton Wooden Hopper Car Prairie Locomotive Works NIB
$39.99
Time Remaining: 10d 10h
Buy It Now for only: $39.99
Blackstone Models HOn3 East Broad Top 3 Bay Hopper Weathered Rd 951 B340703W
Blackstone Models HOn3 East Broad Top 3 Bay Hopper Weathered Rd 951 B340703W
$59.95
Time Remaining: 24d 9h 42m
Buy It Now for only: $59.95
HOn3 EAST BOARD TOP 3 BAY HOPPER CAR KIT BY CBT MODELS
HOn3 EAST BOARD TOP 3 BAY HOPPER CAR KIT BY CBT MODELS
$26.55
Time Remaining: 26d 16h 13m
Buy It Now for only: $26.55

Other On30 Scale train items recently purchased through this site:

On30 5 Ton Wooden Hopper Car Prairie Locomotive Works NIB
Blackstone Models HOn3 East Broad Top 3 Bay Hopper Weathered Rd 951 B340703W
HOn3 EAST BOARD TOP 3 BAY HOPPER CAR KIT BY CBT MODELS