Who here has leased a Prius...experience?

I currently have a first generation Prius. It has over 150,000 miles so I am thinking about getting another car within a year and am thinking about options.

I love the Prius and would love to buy a new Prius but I don't know if I can afford it. I am wondering if it would be better to lease a Prius and then buy it after the lease is up.

From what I understand, I can get decent monthly payments without putting a huge amount down. Generally, how does it work if you lease a car for three years and after the first year you decide you want to buy it? Do they sell it at book value and credit you what you've paid while leasing it or do you just buy it at book value when the lease has expired?

Also, does credit history have a huge effect on whether or not you're approved to lease? My credit ain't so great because of student loans in default.

Sorry for dense questions but I've never leased a car before. I'm wondering what the advantages are to it as opposed to buying.

Has anybody ever leased a Prius and then bought it? Feedback, advise....anything at this point. As I said, I don't need it anytime soon. I'm just exploring options.