Hey I'm restringing and polishing a couple of my guitars and I realized my fretboards are actually... quite discusting, they've got grundge buildup. Whats the best way to clean this without damaging the surface of the wood and without leaving and type of chemical that could effect the strings? Note: they arent old or classic guitars in any way, just a couple of BC Rich Warlocks.

especially any remedies that dont include going out to a music store to buy a special procudt b/c i'm broke right now, and besides i dont feel like driving to daytona to get myself to a guitar store..