Forget foam- get a Zeplin- Rycote or other similar one. If you are outside, that will be by far your best bet.
You can certainly use those really big thick foam ones as well, but they are really expensive for what you get. The ones that are 2-3 inches thick work quite well, but in the end, not as well as a softie. Oh yeah, they'll cost a lot more than $100 too. Sorry. No cheap way out of this one.
I'd also suggest using Omnis as well- not only for the extended low end, but also because they will be much more forgiving on wind noise.