I am heading with my girlfriend to Mendoza for four days. We are going to do the full-day wine tour one day, and want to do excursions all of the other day: hiking, rafting, horseback riding, paragliding, and possibly mountainbiking. Does anyone have information on average prices for these sorts of things, and would it be better (and/or cheaper) to book them ahead of time or wait until I get there? We'll be there in December. Thanks!