thanks for the info Sleeve, that's pretty reasonable pricing for convention sketches. 3 years ago at Armageddon, Bruce Timm was charging AUS$40 for inked headshots and he took maybe 5 minutes to do them. Jim Lee didn't charge for quick marker head sketches as well (I would have been happy to drop a lot of money for a bust piece) and Matt Clarke charged $50 for bust pieces last year.
Full-on commission of course are more expensive, I'm probably gonna pass on Milne this time unless I suddenly come into some money, if it was maybe a hundred or so I'd be all over it. Thanks again guys, always nice to bounce ideas of people I trust in this sort of thing.