not sure if this will make sense in text...I am not good with the written word as well as the spoken word, but let me try:
Since she is insistent on earning her way (a very good thing you have done there mom!!!) Do some math...figure out how much she is saving by riding her bike and use that $$$ as a gift...make her earn her reward by adding up the savings. If you want to buy something for her now you could go ahead and buy it and deduct the price as she rides. (as a photographer myself I like the camera idea...I am a Canon person and have a little snappy that goes with me everywhere as well as a nicer one for "planned" shots)
I think your winter project idea is awesome...start going with ideas now and hitting the sales at your paint stores for discount paints...
I am a nobody; nobody is perfect, and therefore I am perfect.