Deep cycle Marine battery=$125.00 average cost
12v charger to recharge said deep cycle battery= $30-50.00 for a lower end charger
Cost of electricity at your house to recharge said deep cycle battery=Varies
Cost to replace vehicle alternator= hundreds of dollars in most cases

1 800-900kw Chicago Electric generator= $129.99 ($99.95 on sale at Harbor Freight Tools)
1 gallon of low octane fuel in Co. $2.39
2 stroke oil $1.50 for 6.8oz, or 2 tanks full.
You decide.

As far as cranking amps: A car battery is rated at 540 Cranking amps, but only has 190 cranking amps available (remaining capacity). Your car's starter requires 225 cranking amps to turn engine over.
Result? You're stuck at the airfield. Nuff said.