Warwick Red's are a good set of strings for very little money, used to use them for a while, then tried some others which just sounded better.
Elites Stadium Steels used to be pretty good, and are reasonably priced.
Current faves are D'Addario Pro Steels, but they aren't cheap. Amazon have a 4 string set for around £28-29, where bizarrely, a 5 string set is £26.
IMO, they consistently sound great, and last for months.