Depends on how many switches you need. If it's less than 10 and you have a local Radio Shack, that's your best bet. If you need three or four dozen, you can get a better deal at McMaster, or check out http://www.globalsources.com/manufacturers/DPDT-Rocker-Switch.html for a whole listing of offshore dealers that have really cheap prices for volume purchases.
Radio Shack will be fine for items like toggle switches (they may have four in stock), but if you need a good source for electronic parts, try this: http://www.digikey.com/
Many hobbyist use them and they have everything you could possibly need. You know, there was a time when Tandy Corp (RadioShack) carried enough parts to rebuild a radar set, but now they seem more interested in home entertainment, cells, junk, and etc. How about it old timers, remember Lafayette and Allied Electronics with stores a large as supermarkets?
Rex, yes, indeed, as well as all the kits they used to sell. Built a Lafayette 6 meter transciever as my first ham rig in probably 1963. The good news is that Radio Shack has finally relaized they cannot survive by cellphones alone and corparate policy is now to start uping the stock of electronic parts again. Our local corporate store has just undergone a remodeling in the back and there are now five cabinets with switches, resistors, bulbs and all kinds of stuff I needed to finish my wiring job. I was really surprised at the increase in parts stock so maybe there's hope yet. If I see a ham rig for sale there again, I will know we've come full circle.