Dude, you're underestimating people's work for thinking they can work for you just because they're kind, you should understand how much they're good just for even considering doing free art. I mean, if someone in school you don't even know asked you to make their homework in exchange for nothing, would you do it? And what if, let's say, half of the whole school (a symbology for you and a lot of other users asking for requests to the same user) sent you letters asking "Will you do my homework for free? Thanks", would you even want to answer all those dozens or maybe hundred of letters?
Some of them will only now do commissions. Some cheap. others expensive.