When I was a kid... well, lets just say that class trips have gotten progressively more extravagant over the years. Somehow my kids made it through school without going on any trans-continental or trans-oceanic class trips - at parents' expense, of course!
Not that a few of the teachers didn't try! I'm going to be the humbug of the bunch and say that regardless of your new bike plans, you should take the GOLDEN spoon out of her mouth and tell her to get a lot of babysitting jobs to pay for the trip. Don't confuse what she wants for what she needs.