If you wanna know about selling stuff on dA for nickels and pennies, I'm yer gal. ^^
The thing about commissioning on dA is that you don't have to use the widget. If you just tell people to gift their points directly to you, they can totally give you as little as 1 point as payment for your services, simple as that.
Of course, now I'm wondering why you're asking about this...if this is some sort of strategy to sell super-cheap commissions and make up the difference in volume of sales, I would advise against it (unless you already have a healthy pool of buyers...but if you did, why not just sell normal comms?).
If you want to gauge your own odds of success, though, I'd try this: hold a limited-time event where you give away art by request. Of the number of people that come to you for free art, expect 10% to buy from you EVEN at bit prices (10 pts or less). Expect 3% to buy from you at normal prices (5 bucks and up). If those numbers are good for you, go ahead.
EDIT: And since you asked, here's a link from my most profitable bit sale: https://www.deviantart.com/dokidokitsuna/art/10-POINT-MERMAID-PIXEL-CHEEBS-CLOSED-743330326