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
$73.03
Time Remaining: 4d 23h
Buy It Now for only: $73.03
BACHMANN HAWTHORNE VILLAGE CIVIL WAR COLLECTION THE JEB STUART BOX CAR
BACHMANN HAWTHORNE VILLAGE CIVIL WAR COLLECTION THE JEB STUART BOX CAR
$39.90
Time Remaining: 5d 8h 38m
Buy It Now for only: $39.90
BACHMANN HAWTHORNE VILLAGE CIVIL WAR COLLECTION NORTHERN LIGHTS BOX CAR
BACHMANN HAWTHORNE VILLAGE CIVIL WAR COLLECTION NORTHERN LIGHTS BOX CAR
$29.00
Time Remaining: 5d 9h 49m
Buy It Now for only: $29.00
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
$73.03
Time Remaining: 5d 23h 5m
Buy It Now for only: $73.03
BACHMANN HAWTHORNE VILLAGE CIVIL WAR COLLECTION GENERAL ROBERT E LEE BOX CAR COA
BACHMANN HAWTHORNE VILLAGE CIVIL WAR COLLECTION GENERAL ROBERT E LEE BOX CAR COA
$39.00
Time Remaining: 6d 2h 59m
Buy It Now for only: $39.00
BACHMANN HAWTHORNE VILLAGE CIVIL WAR COLLECTION STONEWALL JACKSON BOX CAR
BACHMANN HAWTHORNE VILLAGE CIVIL WAR COLLECTION STONEWALL JACKSON BOX CAR
$39.00
Time Remaining: 6d 11h 51m
Buy It Now for only: $39.00
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: 6d 14h 52m
Buy It Now for only: $59.99
Hawthorne Village Civil War Confederate Express A Plan For Victory Box Car
Hawthorne Village Civil War Confederate Express A Plan For Victory Box Car
$25.00
Time Remaining: 6d 15h 8m
Hawthorne Village Civil War Confederate Express The JEB Stuart Box Car
Hawthorne Village Civil War Confederate Express The JEB Stuart Box Car
$25.00
Time Remaining: 6d 15h 11m
Hawthorne Village Civil War Confederate Express Stonewall Jackson Box Car
Hawthorne Village Civil War Confederate Express Stonewall Jackson Box Car
$25.00
Time Remaining: 6d 15h 11m
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
$73.03
Time Remaining: 12d 2h 17m
Buy It Now for only: $73.03
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
$73.03
Time Remaining: 17d 4h 41m
Buy It Now for only: $73.03
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
$73.03
Time Remaining: 18d 7h 23m
Buy It Now for only: $73.03
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
$73.03
Time Remaining: 18d 22h 40m
Buy It Now for only: $73.03
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
$66.02
Time Remaining: 21d 7h 42m
Buy It Now for only: $66.02
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: 21d 14h 15m
Buy It Now for only: $36.00
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: 25d 8h 53m
Buy It Now for only: $37.00

Other On30 Scale train items recently purchased through this site:

ON3 ON30 SILVER CITY MODELS DRGW 1872 12 4 WHEEL BOX CAR KIT
On30 Fat Albert Boxcar Conversion to fit Bachmann 18ft flat car
BACHMANN HAWTHORNE VILLAGE CIVIL WAR COLLECTION THE JEB STUART BOX CAR
Bachmann On30 Scale Train 18 Box Car W Murphy Roof Gray 2 box 26553
BACHMANN HAWTHORNE VILLAGE CIVIL WAR COLLECTION NORTHERN LIGHTS BOX CAR
BACHMANN HAWTHORNE VILLAGE CIVIL WAR COLLECTION GENERAL ROBERT E LEE BOX CAR COA
BACHMANN HAWTHORNE VILLAGE CIVIL WAR COLLECTION STONEWALL JACKSON BOX CAR
Hawthorne Village Civil War Confederate Express The JEB Stuart Box Car
HAWTHORNE VILLAGE On30 BACHMANN CONFEDERATE CIVIL WAR J E B STUART BOX CAR 005
Hawthorne Village Civil War Confederate Express A Plan For Victory Box Car
Hawthorne Village Civil War Confederate Express Stonewall Jackson Box Car
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
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 DENVER RIO GRANDE DRGW BOX CAR WAGON 15 nd