What is the price difference between the various types of insulation material (e.g. rock wool, natural wool, polyester, polystyrene batts, etc)?

What is the price difference between the various types of insulation material (e.g. rock wool, natural wool, polyester, polystyrene batts, etc)?

The main types of insulation are: Mineral fibres (rock wool and fibreglass), Cellulose, Polyester, Sheep’s Wool, Polystyrene foam boards, Reflective foils, Spray-on Foam and various combinations of the above types. 

Exact prices should be obtained from your proposed suppliers and it pays to shop around for several quotes. AEF can help with a quotation - https://www.aef.com.au/for-home/insulation/get-a-quote/

Batt Insulation:
Batt insulation always has an R value. Aside from the cost of the R value, different types of batt insulation will have different prices. They will all vary according to their R value, though. As an example, Earthwool is a popular batt insulation. Its retail cost is:
$69 for R-2.0 for a 15.96m2 area
$62.00 for R-3.5 will cover 10.47m2
$87.50 for R-4.0 covers a 12.11m2 area

Foil Insulation:
1350mm wide by 60m long plain foil insulation might cost $115
A 16 pack of 1.2m long by 450mm wide pleated foil insulation may cost $28
R-1.8 batt backed foil insulation for roofs costs around $80 for 12m2 coverage
Again, while there can be a considerable difference in price, one type of foil insulation may be better for one type of insulation than another.

Wool - can provide excellent insulation, it is usually more expensive than fibreglass insulation or cellulose insulation (which is often made from recycled paper products). 

Rockwool - Is generally a costlier insulation. Each type has its advantages and disadvantages. Fibreglass and rockwool do not flatten as quickly as cellulose or wool insulation when exposed to water.

Polyester has the advantage of not releasing breathable fibres so is very safe to install. It is a costlier type. 

Insulation boards are designed for under floors, cavities or can be designed for external use. They are also designed for installing over concrete. Each type is designed slightly differently. Insulation boards designed for external use are usually applied before the cladding. The price can vary from $26 for R-1.0 boards to over $600 for premium boards.