wholesale electricity prices

I'm thinking of doing some 'back of a fag packet' calculations on future cash flow for PAX. I have had a look at the futures prices here:

http://www.asx.com.au/products/futures/electricity/australian/dcyphatrade.htm

Everything is priced in MWHr units. Seems to hover around the $30 to $50 per MWhr mark, except in summer when it can jump to $70, does this sound about right?

I also note that RECs are around the $45 mark at the moment, after a low of below $30 last year. I understand the government is seeking Opposition agreement to its RET changes at the moment so the price could remain volatile for a while.

The way I see it, for every MWHr PAX generates in the future they will receive the whoesale price + the REC price. (This ignores any future carbon costs due to an ETS/CPRS or carbon levy.) At today's rates this would be between $75 to $115, approx, depending on the season, per MWHr.

Any comments on this? Apologies in advance for my minimal research as I am very busy, home renovations and work etc etc.