Congratulations!
Do you have any photos of the car sitting under the tarp? I'm sure that I am not the only one who would like to see what you're getting into!
(and by the way, we only have one rule here on the forum: pictures or it never happened, so post up some pic's to share with everyone.)
Budget about $1,500 to get everything up to date: battery, tires, spark plugs, spark plug tubes, air filter, oil, oil filter, fuel filter, cabin filter, wiper blades, coolant, wheel alignment, brake fluid. Check the brake pads and rotors and replace as necessary. Of course, my cost estimate might vary a bit, especially depending on which tires you select, but it will be somewhere in the range of $1,500.
The only thing you would need to have done at a shop is the tire installation/balance and wheel alignment; everything else you can do yourself using Wayne's 101 Boxster Project book which includes step by step guides. The step by step guides can also be found online here:
https://www.pelicanparts.com/boxster/boxster_tech.htm.
You don't mention if the car was up and running perfectly when it was parked eight years ago? Its rare that a perfectly running car gets parked (it happens, but not typical). More typical is that there was a problem that sidelined the car which was never repaired and so the car just sat parked unprepared. Do you know the history?
Disclosure Statement: FYI - Wayne Dempsey wrote the Boxster book and he also owns Pelican Parts, a great source for all of the parts you might need. Pelican Parts is also the owner of this Forum.
Best of luck and let us know how it goes when you get the car!