Definitely wouldn't pay $80 to rent a car, you're already looking at nearly the cost of a taxi. Personally, though I'm not a particularly rich man, I always choose the taxi over the SkyBus because the SkyBus annoys me.

Just a couple of cocktail bar recommendations in that area: Gin Palace (excellent though really expensive martinis) and The Croft Institute. The Croft Institute is mad science themed, and for the full Melbourne experience it's not just located down a creepy alleyway, it's located down a creepy alleyway off a creepy alleyway off a creepy alleyway off Chinatown. Get a map for that one.