2008 worldcon site selection|
Spoken like a wealthy person. I am comfortable paying $45 for admission and $90 to split two hotel nights with somebody. That comes to $135 for the whole convention. I go ahead and budget a total of $200 (to deal with the unexpected), per each convention. I find the cost of a Worldcon membership to be savagely offensive to me. It's rumored that Torcon is actually giving away a *&^#% surplus of all that ill-gotten cash. A plane fare on top of that is out of the question. It's the kind of money I spend on a vacation once every ten years or so. It's a testament to how wonderful a Worldcon probably is that I would be willing to attend a regionally-local one at all.
All worldcons give away their excess cash, that is how Torcon got some of its surplus, from previous worldcons.
Chicon V gave everyone a $10 rebate.
However you are right, more people will attend if they can drive as opposed to flying. A car is a sunk cost while a plane ticket is an extra expense.
Midwest fans used to drive to west coast worldcons, although there were fewer cons in general back then.