i agree with scubastore.com is good as i've bought a posiedon 1st stage before. fast via DHL and clear ordering process online
would recommend to be more careful with 'critical' equipment (regulator, bcd, computer) as u need to consider how to get them serviced, warranty claims etc. other less critical items like slate, pockets, booties, just buy buy buy since now the USD is down =)
some people go further to look at OEM or china/hk stores (e.g. scubapro could be cheaper there)...
i think in Singapore shops struggle becaus rental isn't cheap and customers don't buy gear on regular basis. imagine buying a bcd then coming back 10 years later! they probably should add value through customer service like having open house, gear configuration workshop, etc.