you should get a filter to protect your lens. If you scratched your lens your heart will ache, but filter can change @ quite cheap prices too. Bought my filter for $15 (58mm) at Click! tampines 1, so I think spending this little amount to protect your lens, it's worth it.
depends on the lens that you are using & how much you r willing to spend. if it's just for protection, then u can just get a normal filter, HOYA will do. but if you are having tele-lens & really into qualilty then go ahead.