Yes Tim, its the same case for most players. The player shops are used in 3 diff ways in my opinion, its used by
A) normal people - selling cards at average prices such as 30gp for level 1 - 5, 30 - 100 for level 6-7, 300-500 for level 8. 500-900 for level 9s, and 900(I wish)- 2000+ for level 10s (note that these prices are just an estimate)
Vaults/Gallery - People who us the shop as a gallery to show off their high level cards or collection of a certain deck/cards (Gilgamesh with gallery of Gilgamesh's... ironically, or Howabe with SE gallery which on a side note does not exist now)
C) Pansies - those that put high levels in theoir shop for insane 99999gp so they can play random trad games without fear of drawing a high level and losing it, but in either case if they did have high levels in a trade game chances are they get "disconnected"
but yea, thats basically what the shop is used for but B and C pretty much suck. if you dont want to sell the cards then why put them so everyone can see? I think the max price should be 10k that way if someone wants to be clever and put an SE or EC card in their shop to show off, then someone can easily come and buy it, but hey I only work here... so have fun =D