So I was approached by my friend the other night, and asked by her if I'd be willing to do the photography for her mother and soon to be step father's wedding. Right now, I have a 18-70mm 3.5 kit lens, and a 75-300mm f4 telephoto. So, I thought it would be a decent rate if she just bought me the Sony 50mm f1.4 to take photos for the wedding for my A-200. I think this is a fair trade, since I've never done any kind of wedding photography before. What are other people's thoughts on this? Reasonable/unreasonable?