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

HOn3 Silver Princess brass Gramps tank car in original box
HOn3 Silver Princess brass Gramps tank car in original box
$65.00
Time Remaining: 12h 9m
Buy It Now for only: $65.00
Lot of 2 BLACKSTONE HOn3 B370110 DRGW UTLX 48 Bettendorf Tank Car Trucks
Lot of 2 BLACKSTONE HOn3 B370110 DRGW UTLX 48 Bettendorf Tank Car Trucks
$33.99
Time Remaining: 3d 10m
Buy It Now for only: $33.99
Bachmann On30 Scale Train Tank Car Tank Car DS Fire Suppression 27122
Bachmann On30 Scale Train Tank Car Tank Car DS Fire Suppression 27122
$45.16
Time Remaining: 5d 6h 1m
Buy It Now for only: $45.16
Bachmann On30 Scale Train Tank Car Tank Car Standard Oil 27131
Bachmann On30 Scale Train Tank Car Tank Car Standard Oil 27131
$45.16
Time Remaining: 5d 6h 3m
Buy It Now for only: $45.16
San Juan Car Co Gramps Tank Car Set 63 88131
San Juan Car Co Gramps Tank Car Set 63 88131
$600.00
Time Remaining: 7d 6h 45m
Buy It Now for only: $600.00
San Juan Car Co Gramps Tank Car Set 88153 88166
San Juan Car Co Gramps Tank Car Set 88153 88166
$500.00
Time Remaining: 7d 6h 57m
Buy It Now for only: $500.00
ON30 AMS Tank Car Shell SCCX A 09
ON30 AMS Tank Car Shell SCCX A 09
$45.00
Time Remaining: 17d 10h 42m
Buy It Now for only: $45.00
ON30 AMS Tank Car Standard Oil 106
ON30 AMS Tank Car Standard Oil 106
$45.00
Time Remaining: 19d 13h 49m
Buy It Now for only: $45.00
Iron Horse Brass HOn3 GRAMPS Frameless Tank Car UNUSED
Iron Horse Brass HOn3 GRAMPS Frameless Tank Car UNUSED
$129.99
Time Remaining: 20d 21h 56m
Buy It Now for only: $129.99
On3 On30 WISEMAN MODEL SERVICES WEST SIDE LUMBER CO OIL TANK CAR 5 KIT
On3 On30 WISEMAN MODEL SERVICES WEST SIDE LUMBER CO OIL TANK CAR 5 KIT
$89.95
Time Remaining: 21d 8h 15m
Buy It Now for only: $89.95
Iron Horse Brass HOn3 GRAMPS Frameless Tank Car UNUSED
Iron Horse Brass HOn3 GRAMPS Frameless Tank Car UNUSED
$119.99
Time Remaining: 28d 21h 39m
Buy It Now for only: $119.99

Other On30 Scale train items recently purchased through this site:

ON30 AMS Tank Car Standard Oil 106
ON30 AMS Tank Car Shell SCCX A 09
San Juan Car Co Gramps Tank Car Set 88153 88166
On3 On30 WISEMAN MODEL SERVICES WEST SIDE LUMBER CO OIL TANK CAR 5 KIT
San Juan Car Co Gramps Tank Car Set 63 88131
Bachmann On30 Scale Train Tank Car Tank Car Standard Oil 27131
Lot of 2 BLACKSTONE HOn3 B370110 DRGW UTLX 48 Bettendorf Tank Car Trucks
HOn3 Silver Princess brass Gramps tank car in original box
Bachmann On30 Scale Train Tank Car Tank Car DS Fire Suppression 27122
Iron Horse Brass HOn3 GRAMPS Frameless Tank Car UNUSED
Iron Horse Brass HOn3 GRAMPS Frameless Tank Car UNUSED