To this I personally do not have the answer, it's not my position/job to figure it out. I have seen many other recommendations and calculations presented by other players, all can be considered. When the community is excited to participate, and it's not underpriced, that's the 'right' price. Finding that price... this is the 'market research' that needs to be done by the company, it's something most companies that are in sales do on a regular basis as standard procedure. Price should be a lot more in line with 'actual card value' imo.
Scarcity should not be something we try to force through high price for most items (we see these prices do not hold up on the market), but something that happens naturally as player base and demand increases. Again, I think it's fine to do with SOME items. For SOME sales. But not all the time. We SHOULD have a VIP club, with rare and expensive stuff. But we NEED to ensure access for low level players by offering plenty of reasonably priced, affordable items as well.