Really excellent gameplay loop. You could have a hit on your hands for sure. However there are many instances where the inventory of others I see just don't make sense.
I bring this up out of respect and the feedback is meant to be constructive.
Are people duping in this game? Is there a way to refresh the store without paying? Are you collecting data for the inventory presented and purchase patterns for players?
Viewing post in Backpack Battles Demo comments
if you see someone with a lot of one item, that comes from pure luck, if someone has a lot of items stage on, they got a few lucky sales (50% off). even though some of this game is luck it also has some skill involved, learn what items go well with each other, see what is easy to start or build into. If you are worried about winning the first few rounds, a good start as the hunter is two wooden swords with a whetstone increasing both swords' damage. :)