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'.

HAWTHORNE VILLAGE BACHMANN CONFEDERATE CIVIL WAR NORTHERN LIGHTS BOX CAR 02
HAWTHORNE VILLAGE BACHMANN CONFEDERATE CIVIL WAR NORTHERN LIGHTS BOX CAR 02
$27.97
Time Remaining: 4d 11h 7m
Buy It Now for only: $38.00
H O Scale Hawthorne Village Coke Coco Cola Santa Train Freight Box Car
H O Scale Hawthorne Village Coke Coco Cola Santa Train Freight Box Car
$49.99
Time Remaining: 4d 15h 53m
Buy It Now for only: $49.99
On30On3 Narrow Gauge Custom Scratch Built On30 Boxcar and Caboose Nice Details
On30On3 Narrow Gauge Custom Scratch Built On30 Boxcar and Caboose Nice Details
$185.00
Time Remaining: 5d 20h 53m
Buy It Now for only: $185.00
Bachmann ON30 Logging  Mining cars die cast Woodside dump car 3 per box item
Bachmann ON30 Logging Mining cars die cast Woodside dump car 3 per box item
$39.95
Time Remaining: 6d 9h 4m
BINKLEY KIT BUILT HOn3 NARROW GAUGE DENVER RIO GRANDE DRGW BOX CAR WAGON 15 nd
BINKLEY KIT BUILT HOn3 NARROW GAUGE DENVER RIO GRANDE DRGW BOX CAR WAGON 15 nd
$71.66
Time Remaining: 8d 4h 6m
Buy It Now for only: $71.66
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: 8d 15h 59m
Buy It Now for only: $36.00
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
$71.66
Time Remaining: 9d 4h 11m
Buy It Now for only: $71.66
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: 9d 19h 58m
Buy It Now for only: $59.99
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
$61.64
Time Remaining: 11d 16h 50m
Buy It Now for only: $61.64
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
$67.00
Time Remaining: 11d 16h 50m
Buy It Now for only: $67.00
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
$71.66
Time Remaining: 15d 7h 23m
Buy It Now for only: $71.66
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 606
$71.66
Time Remaining: 19d 8h 27m
Buy It Now for only: $71.66
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
$71.66
Time Remaining: 21d 12h 29m
Buy It Now for only: $71.66
HOn3 Wooden Boxcar Built
HOn3 Wooden Boxcar Built
$29.99
Time Remaining: 22d 31m
Buy It Now for only: $29.99
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
$71.61
Time Remaining: 22d 3h 46m
Buy It Now for only: $71.61
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
$73.15
Time Remaining: 24d 12h 48m
Buy It Now for only: $73.15
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: 28d 13h 59m
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
HAWTHORNE VILLAGE BACHMANN CONFEDERATE CIVIL WAR NORTHERN LIGHTS BOX CAR 02
Bachmann ON30 Logging Mining cars die cast Woodside dump car 3 per box item
H O Scale Hawthorne Village Coke Coco Cola Santa Train Freight Box Car
Bachmann On30 Scale Train 18 Box Car W Murphy Roof Gray 2 box 26553
Bachmann On30 Scale Train Mining Wood Side Dump Cars 3 per box 29801
HAWTHORNE VILLAGE On30 BACHMANN CONFEDERATE CIVIL WAR J E B STUART BOX CAR 005
HOn3 Wooden Boxcar Built
Bachmann On30 Scale Train Logging Mining Cars V Dump Cars 3 per box 29802
On30On3 Narrow Gauge Custom Scratch Built On30 Boxcar and Caboose Nice Details
BINKLEY KIT BUILT HOn3 NARROW GAUGE DENVER RIO GRANDE DRGW BOX CAR WAGON 15 nd
BINKLEY KIT BUILT HOn3 NARROW GAUGE DENVER RIO GRANDE DRGW BOX CAR WAGON 3145 n
BINKLEY KIT BUILT HOn3 NARROW GAUGE DSPPRR DENVER SOUTH PARK REEFER BOX CAR 605
BINKLEY KIT BUILT HOn3 NARROW GAUGE DENVER RIO GRANDE DRGW BOX CAR WAGON 315 nd
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 603