On Level 2 at Island Plaza you can find Mr DIY. It’s been there about four weeks, but I finally made it there yesterday.
For some smaller things, such as caps, it is cheaper than Daiso (Level 3, Gurney Plaza) which charges RM5 for everything. It’s worth a browse to see if they stock the kind of things you need.
Local hardware stores can be good, but their selection and range is relatively small. Still, Ace Hardware in Queensbay Mall has the best hardware selection, but their prices are usually far higher than Daiso or Mr DIY, should they have what you need.