Your not going to readily find a Urethane O-ring provider "cheap"
They are very expensive! Most "mom and pop" oring providers you see online wont even stock them....
DoodleBugSportz has some Complete Luxe Seal kits available.
**** Doh - I see Ragin got ya sorted out.
My Current Markers:
(Exclusively Using Monkey Poo Lube
/ Gun Sav Lube
MacDev Clone GT
Black/Green = Ninja Air 550psi 70/4500 = Seed Rotor
Black/Green (Pooty51 Polished NDZ Can/BubbleGum Flat Face Bolt) = Ninja Air 550psi 70/4500 = Seed Rotor
Black/Green = Ninja 550psi Reg'd Crossfire 70/4500 = Seed Rotor
DigiCam Midnight (Virtue OLED) = Ninja Air 68/4500 = Seed Rotor
Midnight = Ninja Air 68/4500 = Seed Rotor
Champagne (Pooty51 Polished Bolt / Virtue OLED) = Ninja Reg'd CrossFire 70/4500 = Seed Rotor
. . BattleField Orlando