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: 3d 1h 41m
Buy It Now for only: $99.95
PECO SL E191 RIGHT HAND  SL E192 LEFT HAND SMALL RADIUS ELECTROFROG 2R 3L
PECO SL E191 RIGHT HAND SL E192 LEFT HAND SMALL RADIUS ELECTROFROG 2R 3L
$54.99
Time Remaining: 22d 15h 21m
Buy It Now for only: $54.99
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: 27d 19m
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: 27d 47m
Buy It Now for only: $89.95

Other On30 Scale train items recently purchased through this site:

PECO SL E191 RIGHT HAND SL E192 LEFT HAND SMALL RADIUS ELECTROFROG 2R 3L
On3 On30 WISEMAN MODEL SERVICES COLORADO SOUTHERN PASSENGER COACH 70 KIT
On3 On30 WISEMAN SM 108 SHORTY COACH OPEN PLATFORM PASSENGER CAR KIT
On3 On30 WISEMAN SM 101 DRGW OPEN PLATFORM BAGGAGE PASSENGER CAR KIT