http://www.snap-step1.usda.gov/fns/Here's the gov screening tool thingy. Its fairly accurate as far as I know. My sister and her family
almost qualified. They made literally $27 a month too much to get any assistance. Pretty freaking sad considering my sister was (now disabled) and my bro in law is in the coast guard and has been for 12 years now. You'd think he should make enough money. And no, he's not a peon, he works very, very hard and takes every advancement opportunity possible. But anyhow, she used the screening thing and it said they might be eligible, but it was too close to tell. So give it a try. If you income fluctuates, I am not sure how you prove that sort of thing, so I don't know how you would go about that part of it, but give it a try PT. Its what we all pay taxes for.
Edit: Remember though, they will never give you a ton of money, not unless you have children. They don't expect a grown man to need to drink 4 gallons of milk a week or whatever. I've known people who've gotten ridiculous amounts like $14 a month.