Yes they have, we have a whole thread about that called "adventures in the dollar bin". But only go if you don't mind feeling overly jealous of someone's lucky find.
Also, the flippers who make money don't do it the way you do. You won't find gold bin diving too much. The way flippers have made money is in those integers between 9.4-9.8 grades on key books. They will spend thousands on a Giant Size X-Men 1 in 9.6. Crack it out of it's CGC case, press it and regrade it. if it comes out 9.8 then they doubled their money. Flipping any other way is probably more effort than it's worth.
And to answer your other question a 1$ raw comic can be worth more in a CGC case IF it becomes a 9.8. But then you have to remember not just the appearances and comics that matter but also make sure it has a chance at 9.8. because if not, then the comic's value will not increase on par with what it cost to slab.
Here's a key you might find in a dollar bin, New X-Men 134. A flipper found it and sent it to CGC, paid anywhere between $30-$40 alltogether in terms of expenses.
And because it came back 9.6, it sold for only $19, so money was lost. So don't waste your time on dollar bin books and counting pennies, concentrate on bigger books that have interest now (like Detective Comics 359, Ultimate Fallout 4, ect) and flip those.