Average cost of mining per BTC over time Are there any approximations to the average cost of mining of a BTC over time?

The reason I ask is because I think that as this ratio will affect the general availability of  Bitcoins on MtGox, and will be a factor influencing the price.

In other words miners won't sell BTC at a loss, while competition increases and BTCs per block decrease.
This is a chart of blockchain.info's estimated miner operating profit.
The chart makes a number of assumptions which are listed below.

Electricity consumption is estimated based on power consumption of 650 Watts per gigahash and electricity price of 15 cent per kilowatt
hour. In reality some miners will be more or less efficient.
For profit margin hardware costs are estimated to be $1000 per gigahash every
2 years, and bandwidth $1 per gigahash per year.

It is also entirely possible that miners will start only accepting transactions that pay fees, and possibly increase the amount of fees they take to increase the amount of BTC per block. But the amount of fresh bitcoins taken from mining will almost certainly affect the price.