I have a wishlist that i try to fulfill. Other than that, i search for good deals on pins near me that i can try out and/or fix up. If they are better than a pin in my collection, i keep it and move the replacable pin out. If they dont make the cut, they get sold or traded.
I only have room for about 7-10 (depending on how forgiving my wife is ) if i had room for 100, i would own 100...or probably 105, knowing me!
Good pins last a long time. Pins that dont agree with me get moved quickly. It is hard to say how long my average pin lasts. I feel that i have a pretty good lineup for my tastes, so many stay and others move quickly.
Im selling 3 right now, are you looking?