I don't know what kind of relationship you have with your friend. But for me, reselling a bike for more than a friend sells to me, just to make a profit is kind of shady. But that's my opinion.
Perhaps you could buy from your friend, and give it an honest try until you know for sure it won't work for you. Then sell/trade in for a bike that better suits your needs. Either way, I'd be open with your friend about what you plan to do.
Just my 2 cents, take it for what's it worth to you.