Do you mean forceps (gripping/pulling tools), or are you actually thinking about hemostats (scissor-shaped clamps)? Volks sells hemostats in various sizes on the VolksUSA website--they're labeled as "Clip holders." http://www.volksusa.com/tools---materials-assembling.html I know I've seen them on other sites--CoolCat is one. And large hobby/craft stores will probably carry them, as well as medical-supply stores.
I found a kit of them at Michael's a large chain craft store. I also found nice ones at the hardware store (Any ACE hardware should have it.) At the hardware store they were in the section with dremmel tools and x-acto knives They have the locking kind as well, that are called hemostats. They are essential in my stringing technique, personally. I'm actually going to buy another pair Hope this helps!
If you have a local medical supply store, that's where I got mine. I also saw some in the local uniform store..like..medical uniform store. I'm sure there are places online that sell them too.
Another name for them is hemostat; look for them on ebay under that name. You can also buy them here: miniworlddolls.com. Look under Necessities.
I got mine on eBay too for about £2 - they ended up being a bit bigger than I expected but do the job just as well! Shame I can't find them Another good place to find them for cheap is fishing shops if there are any in your area - sadly my area isn't big on fishing, but I know the shop near my parents has a huge range so if you can find a fishing shop then at the very least you can get some idea of sizes before you find a cheaper pair on eBay
Definitely try a local tool or hardware store. The medical supply place here didn't know what a hemostat was, but the tool shops all had them. They aren't very expensive and are a huge help for stringing, especially if you're working alone.
My parents are doctors, and I have tons of them... if your doctor is an OBGYN, next time you visit, ask if they can save some hemostats from a circumcision kit. (typically the kits come with more tools than are needed, so theres leftover 'virgin' tools that otherwise are thrown out... very wasteful, actually)