You can try this place:
Handyman Centre, 1 Scotts Rd., #04-06/07, Shaw Centre. Phone 6737 7815
I find them to have a very well stock range of hardware. Many things that I don't even know what they are call or how they are used. But their price might be slightly more expensive. Well can't expect cheap price around orchard area.
Try the camera shop at Peninsula Shopping Centre. Use the escalator from BATA side (2nd floor). Can't remember the name but is at the opposite end from Alex Foto. Not cheap...abt $18.oo. I got mine there abt a month back.