verdugo136 said:
I'm talking about the blood echoes shop.
It sells stuff based off your progress. For example, I have Depth 4 Dungeons unlocked, so my shop allows me to buy level 2 (and I think some) level 3 materials. I can't buy level 4 materials though.
The weapons are related to the badges you find.
Blood Stones are also sold by progress, the Insight shop is better for that though.
As far as I know it won't stop selling an item, so maybe yours is bugged. I remember mine kept converting any items I bought into Molotov Cocktails for a while. It was kind of frustrating, but lucky for me all the beginning enemies are weak to fire.
EDIT: Actually, if I remember right there are some ritual items they only sell one time.