I know it sounds obvious, but prices will be dictated to by recycle value, their inclusion in meta files SS's included, cards that are in prebuilds, and maybe even UD cards that if purchased could help with file building and go on to be a kind of investment.
I'm not going to let on about the cards I want. As this may inflate the prices. lol
I think the market will suit players such as myself that like to play way out weird files that no one else dare play.
As for prices? That will be down to what you can get for a card. A good 5* I would want around 1000gran a bad one maybe only 500gran.
You would just have to field cards at a high price then see if anyone undercuts you. If they do then you just take it off the market and undercut them.If all you want is a quick sale. I normally try to fix prices at good level.
"The day is becoming disarming searching for harmony. You wanna be balling me but you never get nowhere 'cause I'm killing your whole philosophy"