If it were me, and I HAVE been in your position, I would offer to do an engagement session for them, as your gift, and leave your camera home at the wedding. You said she is a good friend, and you should be enjoying her special day as a friend, not working it. Not only would you be working it, it would be working under very stressful conditions given your inexperience with weddings. You wouldn't be able to enjoy the day, her OTHER friends will be able to to do that, talk to her family and mutual friends, meet new people, you will be running around like a mad man, stressed out. That she isn't willing or able to make photography a budget priority is too bad, but it shouldn't be made your problem. I'm assuming she can't afford a honeymoon, but regardless, the real work in wedding photography takes place AFTER the wedding and while everyone else has the wedding behind them, you are left with a ton of work preparing the photos. Do it only if you have considered all these things, and still WANT to do it, not out of some misguided sense of obligation or sympathy for the bride. I think she has a lot of nerve to ask anyone to do that for free, but that's just my opinion. You can either attend a wedding as a guest or work it, but you can't do both and enjoy the full experience, so pick one. Good luck with your decision.