Egg trays are used as diffuser. You will need absorption panel and also bass trapper.
To treat a room, you will need to study the room first. Usually we place the diffuser on the first reflection point of ur front speakers and also the rear of the floor standing speakers.
As for the back, u can use absorption panels ...n add a few pieces of bass trappers for the room if needed.

I sell Auralex panels. but u can get DIY material to save some money ..not much though

alternatively, you can visit worldfloor in puchong. they have acoustic wall panel.

http://worldfloor.com.my/catalog/20-AC-BOA...OUSTIC-CONCEPT/

i've seen them and they look rather good.

hi sliver2c, usually branded acoustic panels are not cheap.
But I've tried doing the DIY panel myself using high quality rock wool (4' x 8' is RM350). Using this 4' x8', u can cut it out into two 4'x 2. But then u will need to make the frame using MDF board and laminate it using fabric.

In the end, the cost per piece for 4x2 will be around RM200.

As for Auralex, 4x2 diffuser is below RM180. And you get discount on bulk purchase say 10 pieces. PLUS, it's a quality foam engineered by professional. 
Check out http://www.auralex.com/

hi silver,
  before I PM u the best price. This is what I need to know from you.

1) Give me the dimension of your room.
2) What is in your room? say cabinet, how many sofas, tables? roughly give me the items.
3) the construction of the 4 walls in ur room ...say ..2 walls, 1 wall + 2 windows, 2 sliding doors, ...

Basically I need to know wat kind of room u have before i quote u the price coz you might not need so many diffusors after all. you will probably need some bass traps and absorbers.