I've been on both sides of the camera.
When I was a student I had a girlfiend who was on a photography course so she got some practice taking erotic photos of me. I loved every minute of it - makes you feel very sexy and uninhibited. I found myself getting pretty outrageous in front of the camera (egged on by her of course) She wanted to explore all sorts of stuff which was fine by me. Nude, semi nude, erotic, artistic. She also persuaded me to try out some Robert Mapplethorpe type poses for her. Google that if you want, but set your preferances to "uncensored". Anything she showed publicly she cropped to keep it anonymous. That side of it was also quite a secret thrill.
I'm quite keen on photography myself too, and I love doing nude / erotic studies. With girlfriends the sessons can be pretty fun, and generally send up with some steamy sex afterwards as it's arousing for both sides. When I agree to take pictures of anyone I'm not in a relationship with I have a strict no touching rule and treat it entirely professionally. I also make sure both parties sign an agreement based on what we've discussed beforehand, plus I prefer the model to bring a friend. That way you keep it business like and avoid any chances of accusations or misunderstandings. You have to be pretty careful.
I'd advise you to go for it crayola! You'll be glad you did in future, like you say "whilst you have the figure" It'll be something nice to look back on later and quite exciting for you now. Instead of paying, you might get them done free by finding a student on a photograaphy degree for example. Do a deal. They get the practice with a free model, you get the intelectual rights of the images plus a set of prints. They get a set of prints and the practical experience. Find a third year student, and one that's interested in life studies. And use the safeguards I mentioned.
Hope that helps.