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'.

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: 1d 10h 35m
Buy It Now for only: $99.95
Logging Crane small Log Loading crane for a loading dock or flatcar HO BUILT UP
Logging Crane small Log Loading crane for a loading dock or flatcar HO BUILT UP
$49.99
Time Remaining: 12d 17h 32m
Buy It Now for only: $49.99
Kato N Gauge 10 1436 Hankyu 6300 Type with Small Window 8 Cars Set
Kato N Gauge 10 1436 Hankyu 6300 Type with Small Window 8 Cars Set
$178.93
Time Remaining: 19d 10h 41m
Buy It Now for only: $178.93
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: 25d 9h 13m
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: 25d 9h 41m
Buy It Now for only: $89.95

Other On30 Scale train items recently purchased through this site:

Logging Crane small Log Loading crane for a loading dock or flatcar HO BUILT UP
On3 On30 WISEMAN SM 101 DRGW OPEN PLATFORM BAGGAGE PASSENGER CAR KIT
Kato N Gauge 10 1436 Hankyu 6300 Type with Small Window 8 Cars Set
On3 On30 WISEMAN MODEL SERVICES COLORADO SOUTHERN PASSENGER COACH 70 KIT
On3 On30 WISEMAN SM 108 SHORTY COACH OPEN PLATFORM PASSENGER CAR KIT