I live in Seri Petaling and the only good hobby shop around here is Glory System Enterprise (Aunty Lenny). Her prices are quite reasonable compared to other shops and she's very friendly also. Her wares include Gundam kits, revoltechs, Transformers, Saint Seiya, paint, modeling tools, and some other stuff. I've been her customer for almost 3 years already.

Of course, the cheapest method is still buying online. But if you don't like dealing online, aunty's shop is one of the better choices out there.

Here's her shop's address:

Lot 3-083A, 3rd Floor,
Endah Parade,
No.1, Jalan 1/149E,
Bandar Baru Sri Petaling,
57000 Kuala Lumpur.

PS - I still think its a funny name for a hobby shop, sounds more like an IT company.