I just bought my daughter a mountain bike (at a garage sale) a Fuji Thrill with Shimano gears. Anyway we need to replace the right hand shift/brake combo lever(the little spring is shot and won't allow changing of gears). It is a 3 x 7(with a little window to see the #'s 1-7 with a green indicator). The guy at the bike store suggested a Shimano EF60 but I need to buy both and change all the wiring. I can do the work but would rather only replace the broken one. Any ideas on where I can find a part online and what the part # would be?
If you don't want to order it through your LBS (local bike shop), eBay and Google shopping are often reasonably good places to start looking for parts. The number your LBS gave you (EF60) is sufficient to find the right part in this case (you just want the right shifter, but they are sold in pairs, so look for something like "right EF60").
It's not directly related to the question you asked, but now might also be a good time to replace the shift cable as well (since you will need to remove at least the rear one anyway--that might be why the guy at the LBS suggested it). Shift cables are fairly inexpensive--my LBS sells them to me for about $1 each.
Also, since the pair only costs about $20, I'm not sure you really come out ahead by buying just the right one. First, buying just one of a bike part sold in pairs often costs much more than half the price of the pair. Second, shipping just one will probably cost about 75% of shipping both (since this is a fairly small and light item). If you ever need to replace the left shifter, you will be much better off if you had just bought the pair in the first place.
Finally, if you aren't already familiar with the procedure for installing a adjusting indexed shifters, pick up a copy of Zinn's book. (Zinn and the Art of...)
In the UK you can buy OEM R/H only:
(That is the 8 speed that will work fine on 7).
Here is the tech.doc:
The part number is ST-EF60-7 - ask your LBS to order the part in for you, off the top of his/her head the sales staff may not know this can be ordered, but it almost certainly can, and definitely can in the UK.