Hot Wheels. Wow, I used to love them when I was a kid. I've never heard of them coming in "bulk" so I'd just check out your local toy stores, maybe they have a package of many to choose from.
I have seen them at BJ's wholesale. It's something like 100 cars for $25. It's a huge set. I have seen a HULK car collection too, but it may be Matchbox. Not sure if you need Hotwheels or anything like it. Let me know.
