At today's exchange rate of ~800 USD/BTC, this is 0.7 cents.
Thanks.
For a standard implementation, the size is closer to 250 bytes, so 50 times higher. That means 35 cents.
Hoewever, most pools are very well connected, at least to other pools, so that drops it down again.
* "cost" is in quotations because it's not really a cost per se, but a reduction in expected revenue
It is a cost that should be accounted for.