cost (v.)
late 14c., from Old French coster (Modern French coûter) "to cost," from cost (see cost (n.)).
cost (n.)
c. 1200, from Old French cost (12c., Modern French coût) "cost, outlay, expenditure; hardship, trouble," from Vulgar Latin *costare, from Latin constare, literally "to stand at" (or with), with a wide range of figurative senses including "to cost." The idiom is the same one used in Modern English when someone says something "stands at X dollars" to mean it sells for X dollars. The Latin word is from com- "with" (see com-) + stare "to stand," from PIE root *sta- "to stand, make or be firm."