I get worried about that too.
But . . .
I have some rules:
1. Appreciate each toy, give it respect.
2. Be picky about what you collect (don't collect things that you remember but had no personal connection with)
3. When it stops being fun and makes you feel ill, take a break.
4. You have your whole life to collect, there is no need to buy everything RIGHT NOW.
5. Make sure to get a good deal. That item will come around again in time, but your money may not.
6. Only display a bit at a time (my personal rule) makes me appreciate everything.
7. Do not talk about toy collecting with people who wont support it.
Years ago I told my whole family about my obsession with Care Bears and I got attacked. I was seen as a baby and childish and immature. Since then I have hidden my collecting from everyone except those who live with me and my mom because she is a collector too.
I figure, life is full of pain and hardship, why not fill it with something that makes me happy . . . toys! When I have had a hard day I am instantly made happy if I go down and look at my toys. It's an easy fix. Don't let other's ideas of how you should live and spend your money affect you.