The only pricey part of this project is the 42-gauge winding wire, which is usually sold in 1/2-pound spools (25,000 feet; these sell for around $30, although you can sometimes find a deal on eBay). It’s pretty unusual to find 42-gauge wire in a guitar shop (even one that specializes in repairs) or electronics store. RadioShack, for example, doesn’t carry anything thinner than 30-gauge wire, which isn’t likely to work, as it’s more than three times as thick as 42-gauge wire (flip to the appendix for a discussion of wire gauges, which can be a little deceptive). That said, you can go a bit thicker than 42-gauge: Folks have built this pickup with wires as thick as 38-gauge, although they needed to add significantly more windings. You can scrounge appropriately thin gauge wire from old relays, out of old TVs, or from older consumer electronics like plug-in hair clippers (42-gauge wire is popular in beefier electromagnets). However, if you don’t know anything about TVs, do not open one up; those large capacitors can hold a deadly charge long after the set has been unplugged.