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: 4d 10h 32m
Buy It Now for only: $39.99
QUALITY CRAFT HOn3 East Broadtop Steel Hopper Kit 2 PACK
QUALITY CRAFT HOn3 East Broadtop Steel Hopper Kit 2 PACK
$29.95
Time Remaining: 27d 11h 13m
Buy It Now for only: $29.95

Other On30 Scale train items recently purchased through this site:

QUALITY CRAFT HOn3 East Broadtop Steel Hopper Kit 2 PACK
On30 5 Ton Wooden Hopper Car Prairie Locomotive Works NIB