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

On3 On30 WISEMAN MODEL SERVICES NCNG SHORTY WHALEBACK TENDER KIT
On3 On30 WISEMAN MODEL SERVICES NCNG SHORTY WHALEBACK TENDER KIT
$49.95
Time Remaining: 11d 19h 58m
Buy It Now for only: $49.95
O SCALE On3 On30 WISEMAN MODEL SERVICES WESTMINSTER KEROSENE LOCOMOTIVE KIT
O SCALE On3 On30 WISEMAN MODEL SERVICES WESTMINSTER KEROSENE LOCOMOTIVE KIT
$37.95
Time Remaining: 16d 9h 53m
Buy It Now for only: $37.95

Other On30 Scale train items recently purchased through this site:

O SCALE On3 On30 WISEMAN MODEL SERVICES WESTMINSTER KEROSENE LOCOMOTIVE KIT
On3 On30 WISEMAN MODEL SERVICES NCNG SHORTY WHALEBACK TENDER KIT