This achievement is specific to Bard's Tale I: Tales of the Unknown.
You just need to spend money (or receive money, in the case of Garth's) at all four shop types. This includes buying, selling, or identifying goods at Garth's, buying a drink at an inn, healing at a temple, and identifying or recharging at Roscoe's.
This will surely come quickly through regular play, but if you're looking to grab it as quickly as possible:
Inn - N19 E23 (and others)
Temple - N18 E17 (and others)
Garth's - N18 E26
Roscoe's - N21 E12
For helpful visualization: https://bardstaleonline.com/bt1/maps/skara-brae