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

CHOOCH ENTERPRISES SMALL TOWN WAREHOUSE KIT 6110 O SCALE 148
CHOOCH ENTERPRISES SMALL TOWN WAREHOUSE KIT 6110 O SCALE 148
$125.00
Time Remaining: 1d 22h 31m
On3 On30 WISEMAN SM 108 SHORTY COACH OPEN PLATFORM PASSENGER CAR KIT
On3 On30 WISEMAN SM 108 SHORTY COACH OPEN PLATFORM PASSENGER CAR KIT
$89.95
Time Remaining: 17d 37m
Buy It Now for only: $89.95
On3 On30 WISEMAN SM 101 DRGW OPEN PLATFORM BAGGAGE PASSENGER CAR KIT
On3 On30 WISEMAN SM 101 DRGW OPEN PLATFORM BAGGAGE PASSENGER CAR KIT
$89.95
Time Remaining: 17d 1h 6m
Buy It Now for only: $89.95
On3 On30 WISEMAN MODEL SERVICES COLORADO  SOUTHERN PASSENGER COACH 70 KIT
On3 On30 WISEMAN MODEL SERVICES COLORADO SOUTHERN PASSENGER COACH 70 KIT
$99.95
Time Remaining: 28d 2h
Buy It Now for only: $99.95

Other On30 Scale train items recently purchased through this site:

CHOOCH ENTERPRISES SMALL TOWN WAREHOUSE KIT 6110 O SCALE 148
On3 On30 WISEMAN SM 101 DRGW OPEN PLATFORM BAGGAGE PASSENGER CAR KIT
On3 On30 WISEMAN MODEL SERVICES COLORADO SOUTHERN PASSENGER COACH 70 KIT
On3 On30 WISEMAN SM 108 SHORTY COACH OPEN PLATFORM PASSENGER CAR KIT