I have no experience working on them buy my father-in-law has a 98' 993 and takes it in for all maintenance. A single oil change cost him 450+ dollars. The clock went out and cost him 500.00 for the diagnosis alone. The battery had some unknown draw on it and killed it. Diagnosis cost him 600 dollars before they even had a fix. They are NOT cheap to maintain from what I've seen.
Beautiful car you picked but you've got some research to do! :D