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

SN3 1 TOMALCO DRGW 3000 SERIES BOX CAR KITPARTIALLY BUILT
SN3 1 TOMALCO DRGW 3000 SERIES BOX CAR KITPARTIALLY BUILT
$25.00
Time Remaining: 19h 12m
Buy It Now for only: $25.00
Bachmann On30 Scale Train Box Car Murphy Roof Oxide Red 2 box 26552
Bachmann On30 Scale Train Box Car Murphy Roof Oxide Red 2 box 26552
$91.82
Time Remaining: 1d 16h 22m
Buy It Now for only: $91.82
Bachmann On30 Scale Train 18 Freight Cars Low Gondola 2 box 26531
Bachmann On30 Scale Train 18 Freight Cars Low Gondola 2 box 26531
$69.24
Time Remaining: 1d 16h 22m
Buy It Now for only: $69.24
Bachmann On30 Scale Train 18 Freight Cars Box Car 2 per box 26501
Bachmann On30 Scale Train 18 Freight Cars Box Car 2 per box 26501
$91.82
Time Remaining: 1d 16h 22m
Buy It Now for only: $91.82
Bachmann On30 Scale Train 18 Box Car W Murphy Roof Gray 2 box 26553
Bachmann On30 Scale Train 18 Box Car W Murphy Roof Gray 2 box 26553
$91.82
Time Remaining: 1d 16h 22m
Buy It Now for only: $91.82
Bachmann On30 Scale Train 18 Freight Cars High Gondola 2 box 26541
Bachmann On30 Scale Train 18 Freight Cars High Gondola 2 box 26541
$74.51
Time Remaining: 1d 16h 22m
Buy It Now for only: $74.51
Bachmann On30 Scale Train Box Car South Pacific Coast Sunset Logo 27002
Bachmann On30 Scale Train Box Car South Pacific Coast Sunset Logo 27002
$45.91
Time Remaining: 1d 16h 24m
Buy It Now for only: $45.91
Bachmann On30 Scale Train Box Car Mineral Red Data Only 27098
Bachmann On30 Scale Train Box Car Mineral Red Data Only 27098
$45.91
Time Remaining: 1d 16h 24m
Buy It Now for only: $45.91
Bachmann On30 Scale Train Box Car Oxide Red Data Only 27097
Bachmann On30 Scale Train Box Car Oxide Red Data Only 27097
$45.91
Time Remaining: 1d 16h 24m
Buy It Now for only: $45.91
Bachmann On30 Scale Train Box Car White Pass  Yukon 27001
Bachmann On30 Scale Train Box Car White Pass Yukon 27001
$45.91
Time Remaining: 1d 16h 24m
Buy It Now for only: $45.91
Bachmann HOn30 Scale Narrow GaugeTrain Box Van Blue 77202 Thomas
Bachmann HOn30 Scale Narrow GaugeTrain Box Van Blue 77202 Thomas
$48.17
Time Remaining: 1d 16h 27m
Buy It Now for only: $48.17
Bachmann HOn30 Scale Narrow Gauge Train Box Van Red 77203 Thomas
Bachmann HOn30 Scale Narrow Gauge Train Box Van Red 77203 Thomas
$48.17
Time Remaining: 1d 16h 27m
Buy It Now for only: $48.17
ON3 ON30 SILVER CITY MODELS DRGW 1872 12 4 WHEEL BOX CAR KIT
ON3 ON30 SILVER CITY MODELS DRGW 1872 12 4 WHEEL BOX CAR KIT
$36.00
Time Remaining: 2d 4h 50m
Buy It Now for only: $36.00
HAWTHORNE VILLAGE On30 BACHMANN CONFEDERATE CIVIL WAR J E B STUART BOX CAR 005
HAWTHORNE VILLAGE On30 BACHMANN CONFEDERATE CIVIL WAR J E B STUART BOX CAR 005
$59.99
Time Remaining: 5d 19h 18m
Buy It Now for only: $59.99
BINKLEY KIT BUILT HOn3 NARROW GAUGE DENVER RIO GRANDE DRGW BOX CAR WAGON 315 nd
BINKLEY KIT BUILT HOn3 NARROW GAUGE DENVER RIO GRANDE DRGW BOX CAR WAGON 315 nd
$66.57
Time Remaining: 7d 7h 49m
Buy It Now for only: $66.57
BINKLEY KIT BUILT HOn3 NARROW GAUGE DSPPRR DENVER SOUTH PARK REEFER BOX CAR 605
BINKLEY KIT BUILT HOn3 NARROW GAUGE DSPPRR DENVER SOUTH PARK REEFER BOX CAR 605
$66.57
Time Remaining: 11d 6h 42m
Buy It Now for only: $66.57
BINKLEY KIT BUILT HOn3 NARROW GAUGE DENVER RIO GRANDE DRGW BOX CAR WAGON 3145 n
BINKLEY KIT BUILT HOn3 NARROW GAUGE DENVER RIO GRANDE DRGW BOX CAR WAGON 3145 n
$66.57
Time Remaining: 12d 4h 3m
Buy It Now for only: $66.57
BINKLEY KIT BUILT HOn3 NARROW GAUGE DSPPRR DENVER SOUTH PARK REEFER BOX CAR 603
BINKLEY KIT BUILT HOn3 NARROW GAUGE DSPPRR DENVER SOUTH PARK REEFER BOX CAR 603
$66.57
Time Remaining: 17d 11h 48m
Buy It Now for only: $66.57
Bachmann On30 Scale Train Mining Wood Side Dump Cars 3 per box 29801
Bachmann On30 Scale Train Mining Wood Side Dump Cars 3 per box 29801
$69.44
Time Remaining: 18d 19h 55m
Buy It Now for only: $69.44
Bachmann On30 Scale Train Logging  Mining Cars V Dump Cars 3 per box 29802
Bachmann On30 Scale Train Logging Mining Cars V Dump Cars 3 per box 29802
$66.27
Time Remaining: 18d 19h 55m
Buy It Now for only: $66.27
On30 Fat Albert Boxcar Conversion to fit Bachmann 18ft flat car
On30 Fat Albert Boxcar Conversion to fit Bachmann 18ft flat car
$37.00
Time Remaining: 24d 13h 19m
Buy It Now for only: $37.00

Other On30 Scale train items recently purchased through this site:

On30 Fat Albert Boxcar Conversion to fit Bachmann 18ft flat car
ON3 ON30 SILVER CITY MODELS DRGW 1872 12 4 WHEEL BOX CAR KIT
SN3 1 TOMALCO DRGW 3000 SERIES BOX CAR KITPARTIALLY BUILT
Bachmann On30 Scale Train Box Car Oxide Red Data Only 27097
Bachmann On30 Scale Train Box Car Murphy Roof Oxide Red 2 box 26552
Bachmann On30 Scale Train 18 Freight Cars Box Car 2 per box 26501
Bachmann On30 Scale Train Box Car Mineral Red Data Only 27098
Bachmann On30 Scale Train Box Car South Pacific Coast Sunset Logo 27002
BINKLEY KIT BUILT HOn3 NARROW GAUGE DENVER RIO GRANDE DRGW BOX CAR WAGON 3145 n
BINKLEY KIT BUILT HOn3 NARROW GAUGE DENVER RIO GRANDE DRGW BOX CAR WAGON 315 nd
Bachmann On30 Scale Train Box Car White Pass Yukon 27001
Bachmann On30 Scale Train 18 Freight Cars High Gondola 2 box 26541
Bachmann On30 Scale Train Mining Wood Side Dump Cars 3 per box 29801
On3 On30 CRAFTSMAN WISEMAN COLORADO SOUTHERN RIO GRANDE SOUTHERN BOXCAR KIT
Bachmann On30 Scale Train 18 Box Car W Murphy Roof Gray 2 box 26553
Bachmann On30 Scale Train Logging Mining Cars V Dump Cars 3 per box 29802
Bachmann On30 Scale Train 18 Freight Cars Low Gondola 2 box 26531
HAWTHORNE VILLAGE On30 BACHMANN CONFEDERATE CIVIL WAR J E B STUART BOX CAR 005
Bachmann On30 Scale Train Mining Wood Side Dump Cars 3 per box 29801
BINKLEY KIT BUILT HOn3 NARROW GAUGE DSPPRR DENVER SOUTH PARK REEFER BOX CAR 603
Bachmann HOn30 Scale Narrow GaugeTrain Box Van Blue 77202 Thomas
Bachmann HOn30 Scale Narrow Gauge Train Box Van Red 77203 Thomas
BINKLEY KIT BUILT HOn3 NARROW GAUGE DSPPRR DENVER SOUTH PARK REEFER BOX CAR 606
BINKLEY KIT BUILT HOn3 NARROW GAUGE DSPPRR DENVER SOUTH PARK REEFER BOX CAR 605