Why is it elitist? Loads of schools offer trips of varying sorts. Sometimes it's an opportunity for a family to give their child an experience like this as they are able to scrape money together for the child to go but not whole family. Therefore the child is able to have experience that they wouldn't have had. Someone I know said that they could allow each of their two children a chance to go abroad because of school trips, something they couldn't afford if the three of them went together.
Nowadays a school if a child wishes to go who cannot afford a trip the school will often assist financially in some form. Income cases the whole trip may be funded (and, yes, this does happen in state schools).
Just because one person can't go does that mean no-one should have the opportunity?
Going skiing isn't elitist. Going skiing and choosing only hugely expensive resorts in the most expensive countries absolutely is.
In my opinion the school should have an obligation to deliver activities as cost effectively as possible