imo its absolutely valid to pay artists in premium currency, some people who really enjoy a game might even prefer it a lot over rlc

anyways, i am interested, but as many have asked already:
how much time do you expect new artists to work / be available and whats the workload?
also, i have absolutely no clue about commercial rates, whats fair and what isnt, as so far ive only been paid by friends and family for art and did everything else for premium currency on other games, so can anyone maybe give me an idea of how to price myself fairly?