Well ,since they are probably selling stuff in this shop ,so they would simply use ' it can be bought " in our shop or even ' you can buy it , or ' we have it ' ,,,, that is the way they would be speaking then.
Linguistically correct are both ' purchased' and 'obtained'
"Purchased" means you can close the deal and buy it , referring in particular to act of purchase .
"Obtained" means it is available here and you can have it .It refers to the availability of the item or good .