hey there, try the etymotic research ER-20 ear plugs at Hung Brothers, Sim Lim square. $25 a pair - i know its like, 10 time more expensive than regular plugs but they are definitely more than 10 times better. they attenuate volume but preserve clarity, great for jamming and even going to gigs etc. not as uncomfortable / weird as normal ear plugs, once you break them in after wearing them a few times.
headphone/earmuff style protectors generally just attenuate volume but don't preserve clarity - you'll be overcompensating certain frequencies and may end up having a really crap guitar sound, not to mention your bandmates will start to complain and whine about how come your guitar suddenly sounds like crap.