Invest vs. Buy a motorcycle

Lets say that you have $3-10 thousand. You check out craigslist for motorcycles and see a clean Kawi 900cc. Then you head over to LazyManAndMoney and get jealous that he's already making more than $300 every month from passive income. $8000 in prosper (at 15% ROI) could get you around $100 in monthly passive income. Hard choice!

Here's what I would do:
Start investing into prosper, $8000 is going to take a while to win bids, especially if you're going for 15% risk adjusted. Use prosper or other cheap lending option to get the bike at say 8%. Woo-hoo! Now you're making 7% off of $8000 which is a cool $45 a month passive income. This is great. How come no one thought of this before? Well...there is one small gotcha: You have to pay taxes on the full 15%; inflation kills off another 2.5%; the risk is some what unknown on prosper; prosper charges 1% at the front of the loan; it'll easily cost you $45 a month in insurance for your new bike; it takes time and effort to find borrowers that you trust. Eek! Suddenly this is sounding like a bad idea.