Indie Game Artist / Telegram: vinfang
I had someone do some thing similar a while back too! I still offer a preliminary sketch before I send invoices but I wonder if that's something that's even worth my time? Like I just want all the details before-hand so when I ink there's no major changes after but I'd hate to have it happen again
I have similar experience, client wants to get some not-yet-drawn concept art for his OCs, we chat a bit (about art style/ his vision/ prices, etc), i then sent a sketch, and asked for money. his reply is something like "oh well, I want to take some more time and look at other artist 's stuff too. it's still too soon to make my pick."
not too mad, but he wasted my time for sure.