i just buy bulk individual strings from musician's friend or similar. for about 2.50 a set or so, i get the gauges i want (which do not exist in prematched sets). i keep them clean fairly religiously (using fast fret or some other cleaner/protectant to wipe them down with and then to coat them with), and they stay brighter longer than those of any of my friends' guitars. and if i feel like changing them, it's way too cheap for even a po' boy like me to have reservations about!