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

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
$67.57
Time Remaining: 4d 8h 6m
Buy It Now for only: $67.57
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
$67.57
Time Remaining: 5d 8h 11m
Buy It Now for only: $67.57
HAWTHORNE VILLAGE On30 BACHMANN CONFEDERATE CIVIL WAR J E B STUART BOX
HAWTHORNE VILLAGE On30 BACHMANN CONFEDERATE CIVIL WAR J E B STUART BOX
$59.99
Time Remaining: 5d 23h 58m
Buy It Now for only: $59.99
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
$67.57
Time Remaining: 11d 11h 22m
Buy It Now for only: $67.57
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
$68.36
Time Remaining: 16d 13h 47m
Buy It Now for only: $68.36
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
$67.57
Time Remaining: 17d 16h 28m
Buy It Now for only: $67.57
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
$67.57
Time Remaining: 18d 7h 46m
Buy It Now for only: $67.57
MERRY CHRISTMAS TO ALL BOXCAR HAWTHORNE RUDOLPHS CHRISTMAS TOWN EXPRESS NIB
MERRY CHRISTMAS TO ALL BOXCAR HAWTHORNE RUDOLPHS CHRISTMAS TOWN EXPRESS NIB
$84.99
Time Remaining: 19d 18h 45m
Buy It Now for only: $84.99
RUDOLPHS  ABOMINABLE SNOW MONSTER CHRISTMAS TOWN EXPRESS BOX CAR
RUDOLPHS ABOMINABLE SNOW MONSTER CHRISTMAS TOWN EXPRESS BOX CAR
$59.99
Time Remaining: 21d 14h 16m
Buy It Now for only: $59.99
BACHMANN HAWTHORNE VILLAGE THE CONFEDERATE GENERAL ROBERT E LEE BOX CAR
BACHMANN HAWTHORNE VILLAGE THE CONFEDERATE GENERAL ROBERT E LEE BOX CAR
$25.00
Time Remaining: 24d 13h 54m
Buy It Now for only: $25.00
New Hawthorne Village Train Dumbos Box Car Disney
New Hawthorne Village Train Dumbos Box Car Disney
$39.99
Time Remaining: 24d 14h 27m
Buy It Now for only: $39.99
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 17h 59m
Buy It Now for only: $37.00
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: 24d 23h 20m
Buy It Now for only: $36.00

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
MERRY CHRISTMAS TO ALL BOXCAR HAWTHORNE RUDOLPHS CHRISTMAS TOWN EXPRESS NIB
RUDOLPHS ABOMINABLE SNOW MONSTER CHRISTMAS TOWN EXPRESS BOX CAR
BACHMANN HAWTHORNE VILLAGE THE CONFEDERATE GENERAL ROBERT E LEE BOX CAR
New Hawthorne Village Train Dumbos Box Car Disney
HAWTHORNE VILLAGE On30 BACHMANN CONFEDERATE CIVIL WAR J E B STUART BOX CAR 005
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 3145 n
BINKLEY KIT BUILT HOn3 NARROW GAUGE DSPPRR DENVER SOUTH PARK REEFER BOX CAR 603
BINKLEY KIT BUILT HOn3 NARROW GAUGE DENVER RIO GRANDE DRGW BOX CAR WAGON 15 nd
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 606