Maybe this will work...or check the associated "what other folks also bought" pages. You may be able to remove and re-use the bulb for your trimmer. If it works let me know.
http://www21.shopping.com/xPO-McCulloch-Ryobi-Idc-Ryan-Mcculloch-Snap-In-Primer-Bulb-10006-b
T, November 2009