So I've read a few magazine articles and the website for Gimpel's PC-lint and Flexelint C/C++ compiler.
It's really expensive (at least for me), but it seems like it might have some merit to warrant the cost.
So I'm wondering if anyone else has used/bought them and can provide their opinions?
I used to use PC-Lint a while ago. Personally I think it was worth the investment. Part of the answer to your question depends on a few other factors:
1.) Have you tried turning up the compiler warning level to the highest level? Very annoying but this has the effect of catching any obvious semantic errors. I'd do this before I invested in a specialized tool like PC-Lint
2.) Who are you coding for? If this is a homework assignment for school then it's not worth it. If it's software you're selling to others then it's a good investment in producing clean stable code.
Be aware that like any tool it can take some time to learn to use PC-Lint effectively.