How large is the "hole" between your accounts and your expenses? How much "more than $20 here and there" are we talking? And how up are you on trends, brands that are about to explode but haven't yet, etc? IOW, will you be able to spot a $4 shirt that can sell for $50, without googling half the items on the rack to check their pricing? And will you stay up on Owala being the new "it" drinking container, or would you buy the Stanley thinking it's still "in" when it's on the way out and the market is saturated? (That's just an example as it's one of the few trendee things I know.) Can you spot a fake LV/Prada bag vs. a real one, or cut crystal vs. crap? And are you willing to troll thrift stores around town (or three towns over if that's the one that tends to have higher-end items), a few times a week? Are you willing to buy a stained Burberry trench for $20 and hope that you can get it clean so you can sell for $200 but eat the $20 if you can't get out the stains? Do you have a specific skill, like the ability to repair electronics?
if not, or if you must have more than a few hundred dollars a month, I'd say you can find a better way to get it that is more reliable, less stressful, and less risky. Walk dogs, babysit kids, substitute teach, run errands for seniors...