Well, if you look in to resale, it may or may not be worth it. For example, you can start out with a 50 point contract at SSR for around $4000. With EOY plan, that would give you 100 points to use with banking or borrowing. Using the 2010 points chart, that would get you 8 nights in the peak season (mid Feb - mid April) in a preferred site (premiums are more). If you travel at other times, it would be less points so possibly more nights.
I don't know what a campsite costs (have never done it), but this would give you an idea if it is worth it or not. Those 50 points, would cost about $250 in MF's a year.
Good luck!