Was doing my regular browsing at Serangoon Ave North today. Saw this shop that carries nice rocks. They sell cichlids too, but not much. Some of you guys hunting for some nice rocks might want to try there.

I left my DC at home and was unable to take the pictures.
There are some that look like big marble pieces, atleast the grains look alike and they cost $3 per kg

There are nice dark(near black) grain rocks as well and it cost $3 per kg.

These are the real cool one, slight brownish colour, few tones below drift wood colours, those cost $4 per kg.

The average rocks size are about 2-3 kg, you go figure the size.

As always, I grabbed a name card and here are the info.
Lim Pets House
Blk 151 Serangoon North Ave 2
Unit 01-23
Singapore 550151

C.H. Lim
Hp: 97321593

Hope this helps...