guitar connection at peninsular and guitar workshop at bras basah complex both do paintjobs and pickup changes etc. g77 does pickup changes and wiring and i find service there to be the friendliest out of the bunch.
pickup changes are about 10-15 if i remember correctly, if you want it all to be cheaper, just get all the pots and pickups and one shot let them install it.
paintjobs i think it was 400 at gc. i find their prices a very steep but that's just me. eg. fretless job is $200 there, in malaysia tham does it for around rm150 if i remember correctly.