I don't know about you, but I'm not made of sugar therefore I don't melt in the rain. Don't be such a baby!
If you can't afford the $100 no worries, but that's NOT steep... this is my friends own personal bike he's willing to loan out. If you try to rent anywhere in the city, you'll be paying $200 after taxes and insurance, and that will be for a wimpy xr200 or something similar.