a 10 day (9 night) vacation in the summer including 4 weekend nights would require about 500 pts for a standard view 2BR or 660 pts for a 2BR with a magic kingdom view. (
point charts are linked in the top right-hand corner if you want to run some numbers yourself.)
500 pts would start at around $54,000 including closing costs. annual dues for 500 pts would start around $1850 per year.
i believe you would get 50 years of vacations, provided you keep paying your annual dues (which will increase over time).
if you can avoid weekend nights, you can save some money. you could save a little bit by going in the offseason. but with kids in school, that may be difficult.