I have just had a custom house designed that I'll have built soon, and I want to get a feel for how much it will cost. The basement will be constructed using ICFs, including the one walkout wall. The size of the basement is approx 216linear feet with walls 8' 7" high, but the overall building footprint is complex as it is basically the shaped like a cross or "+" so there are 8 external corners and 4 internal corners to add some fun to the build. (doubtless more expensive but beleive me it is a great design).

We intend to use 8" ICfs so any advice regarding material costs and labour would be really great. I am aware that the concrete mix, pour plus rebar will add up to around $10-12k, but I am less clear how much to budget for the ICF materials and the labour associated with the ICF construction and pour.

Many Thanks 

One of the ICF makers, I can't recall which, offers an estimating tool based on wall height and length, number of corners, number of windows.

for a rough estimate count the number of blocks you will need and multiply by $14-18. This will give you a realistic rough, material only, price for the ICF. Corner blocks are about 10-25% more than the straights. The ICF vendors you are considering will give you an actual block size to do this calculation. If you don't have a block picked out then use 16"x48" for this calc. If the block you are considering is substantially different than this size adjust the price accordingly.

Other things to consider:
waste, which is highly dependent on the number of windows & doors.
Brick ledge add 20% to std block
Shipping costs

Labor can only be a guess. It is highly dependent on the contractor you select and the prevailing labor rates in your area. local factors that determine your price: popularity of ICF, jobsite conditions, acceptance by the local code officials, insurance requirements, competition.

http://www.owenscorning.com/foldform/estimator/step1-index.asp

these guys have a materials calculator.