Air-Oil Products has every kind and size O-ring imaginable, you just need to know what size you need.
Click Here for Air-Oil Products O-rings
They have a $1.00 minimum per part number / $5.00 minimum total order
(plus shipping and handling)
Order value $5-$24.99 shipping $7.50
Order value $25.00 - 99.99 shipping $8.50
Order value $100.00 - $249.99 shipping $9.50
Order value $250.00 - $499.99 shipping $12.00
Order value $500.00 - $999.99 shipping $15.00
If you strike out everywhere else, figure out what what material and size you need. I could phone order them, pick them up at their will call, and send to you USPS for a lot
less than the $7.50 shipping. They are just down the road a few miles from me. You would still have the $5 minimum order charge, plus whatever the USPS is though.