For an online source to caster wheel manufacturers, address, phone #s go to:
http://www.thomasregister.com
 
After free membership search "casters" and also "ball casters".  You will
get a listing of companies that manufacturer these.  I have the print
version (with ads) of The Thomas Register and looking through it I would
agree that 1 1/4" are about the smallest readily available.  Some companies
that were interesting offered ball casters and also gliders that seem quite
small.  Would gliders work?  What surface are we trying to make it work on??
One company for gliders is Gross Stabil Corp, 333 Race Street, Coldwater, MI
49036 Phone 517-279-8040.  For the Ball/Transfer casters one company that
looks like they have wide variety and mentions a 11/16" (eleven sixteenths
inch) ball diamter is Acme Caster Company, 68B Fairview Ave, Poughkeepsie NY
12601 Phone 800-472-2263.  MSC Industrial Supply Co.  says they have hard to
find styles in stock, 800-753-7937.  Then there is Casters, Wheels &
Industrial Handling Inc 1-800-MR CASTER or Jilson Casters Inc
1-800-969-5400.  There are casters with shock absorbers too - but they look
to be 2" at minimum.  Good luck...
[Posted in FML issue 1616]