I buy stuff as I need it, or when i see something that looks cool. I go to swap meets, garage sales and flea markets. Ebay and craigslist too. I pick up stuff that just looks cool, especially if it a good price.
I am always on the lookout for tools. Sometimes, I even find them in the street. Freeway on ramps are a good place to watch the outside of the curve. Tools fall off of worktrucks all the time.
If I see it . I'll stop. Just 2 weeks ago I found a nice set of Thomas & Betts crimping pliers in the middle of an intersection....I stopped traffic to rescue that set.
Sitting in freeway traffic is always a good time to scan the shoulder. One day I found a really good set of channel lock water pump pliers.
Sometimes I'll buy a tool even if I already have one....or 2 or 3 or 4. You never know when one will break....and they never break when you don't need it.....Duh
I've been collecting tools since I was 11.
I don't buy too much Harbor Freight or import stuff, but sometimes I have too. If I do, I try to replace it with quality stuff as soon as I can.
You can never have too many tools. As long as you use them. I hate toolbox queens.