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: 2h 19m
Buy It Now for only: $49.95
Kato N Gauge UP FEF 3  844 Black 12605 2 Model Railroad steam Locomotive
Kato N Gauge UP FEF 3 844 Black 12605 2 Model Railroad steam Locomotive
$252.63
Time Remaining: 5d 17h 52m
Buy It Now for only: $252.63
n scale KATO C 62 Sanyo Shape Kure line 2017 5 Train Model steam Locomotive
n scale KATO C 62 Sanyo Shape Kure line 2017 5 Train Model steam Locomotive
$154.72
Time Remaining: 5d 17h 52m
Buy It Now for only: $154.72
KATO N Gauge D51 Standard Form 2016 9 Model Railroad steam Locomotive
KATO N Gauge D51 Standard Form 2016 9 Model Railroad steam Locomotive
$134.52
Time Remaining: 5d 17h 52m
Buy It Now for only: $134.52
kato N gauge EF80 primary 3064 1 model train electric locomotive
kato N gauge EF80 primary 3064 1 model train electric locomotive
$88.93
Time Remaining: 5d 17h 52m
Buy It Now for only: $88.93
Kato N Gauge EF65 1000 Late Model JR 3061 2 Japan Import
Kato N Gauge EF65 1000 Late Model JR 3061 2 Japan Import
$89.69
Time Remaining: 5d 17h 52m
Buy It Now for only: $89.69
Kato N Gauge EF81 General Color 3066 1 Model Railroad Electric Locomotive
Kato N Gauge EF81 General Color 3066 1 Model Railroad Electric Locomotive
$89.62
Time Remaining: 5d 17h 52m
Buy It Now for only: $89.62
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: 6d 8h 7m
Buy It Now for only: $37.95
DRGW Locomotives 15mm F 1203 Model Railroad Water Slide Decal Set SJD254
DRGW Locomotives 15mm F 1203 Model Railroad Water Slide Decal Set SJD254
$32.42
Time Remaining: 8d 16h 47m
Buy It Now for only: $32.42
RGS Sunrise Locomotive 15mm F 1203 Model Railroad Water Slide Decal Set SJD255
RGS Sunrise Locomotive 15mm F 1203 Model Railroad Water Slide Decal Set SJD255
$33.54
Time Remaining: 8d 16h 50m
Buy It Now for only: $33.54
KATO N gauge EF200 appeared during coating 3036 2 model railroad electric locomo
KATO N gauge EF200 appeared during coating 3036 2 model railroad electric locomo
$75.18
Time Remaining: 11d 19h 53m
Buy It Now for only: $75.18
KATO N gauge EF200 appeared during coating 3036 2 model railroad electric locomo
KATO N gauge EF200 appeared during coating 3036 2 model railroad electric locomo
$73.27
Time Remaining: 13d 8h 20m
Buy It Now for only: $73.27
KATO N gauge EF200 appeared during coating 3036 2 model railroad electric 3ir
KATO N gauge EF200 appeared during coating 3036 2 model railroad electric 3ir
$91.09
Time Remaining: 16d 21h 16m
Buy It Now for only: $91.09
KATO N gauge EF200 appeared during coating 3036 2 model railroad electric locomo
KATO N gauge EF200 appeared during coating 3036 2 model railroad electric locomo
$80.46
Time Remaining: 18d 22h 11m
Buy It Now for only: $80.46
Lima Locomotive Works 1913 Ford Model T Rail Inspection Car Kit 148 O Scale
Lima Locomotive Works 1913 Ford Model T Rail Inspection Car Kit 148 O Scale
$38.00
Time Remaining: 20d 22h 29m
Buy It Now for only: $38.00
KATO N gauge UP FEF 3  844 black 12605 2 model railroad steam locomotive
KATO N gauge UP FEF 3 844 black 12605 2 model railroad steam locomotive
$224.25
Time Remaining: 25d 12h 34m
Buy It Now for only: $224.25

Other On30 Scale train items recently purchased through this site:

Lima Locomotive Works 1913 Ford Model T Rail Inspection Car Kit 148 O Scale
O SCALE On3 On30 WISEMAN MODEL SERVICES WESTMINSTER KEROSENE LOCOMOTIVE KIT
DRGW Locomotives 15mm F 1203 Model Railroad Water Slide Decal Set SJD254
On3 On30 WISEMAN MODEL SERVICES NCNG SHORTY WHALEBACK TENDER KIT
RGS Sunrise Locomotive 15mm F 1203 Model Railroad Water Slide Decal Set SJD255
KATO N gauge EF200 appeared during coating 3036 2 model railroad electric locomo
KATO N gauge UP FEF 3 844 black 12605 2 model railroad steam locomotive
KATO N gauge EF200 appeared during coating 3036 2 model railroad electric 3ir
KATO N gauge EF200 appeared during coating 3036 2 model railroad electric locomo
KATO N gauge EF200 appeared during coating 3036 2 model railroad electric locomo
KATO N Gauge D51 Standard Form 2016 9 Model Railroad steam Locomotive
n scale KATO C 62 Sanyo Shape Kure line 2017 5 Train Model steam Locomotive
Kato N Gauge UP FEF 3 844 Black 12605 2 Model Railroad steam Locomotive
kato N gauge EF80 primary 3064 1 model train electric locomotive
Kato N Gauge EF81 General Color 3066 1 Model Railroad Electric Locomotive
Kato N Gauge EF65 1000 Late Model JR 3061 2 Japan Import