Cost
Middle English: from Old French coust (noun), couster (verb), based on Latin constare ‘stand firm, stand at a price’.
wiktionary
From Middle English costen, from Old French coster, couster(“to cost”), from Medieval Latin cōstō, from Latin cōnstō(“stand together”).
From Middle English cost, coust, from costen(“to cost”), from the same source as above.
From Middle English cost, from Old English cost(“option, choice, possibility, manner, way, condition”), from Old Norse kostr(“choice, opportunity, chance, condition, state, quality”), from Proto-Germanic *kustuz(“choice, trial”) (or Proto-Germanic *kustiz(“choice, trial”)), from Proto-Indo-European *ǵéwstus(“to enjoy, taste”).
Cognate with Icelandic kostur, German dialectal Kust(“taste, flavour”), Dutch kust(“choice, choosing”), North Frisian kest(“choice, estimation, virtue”), West Frisian kêst(“article of law, statute”), Old English cyst(“free-will, choice, election, the best of anything, the choicest, picked host, moral excellence, virtue, goodness, generosity, munificence”), Latin gustus(“taste”). Related to choose. Doublet of gusto.
From Middle English[Term?], from Old French coste, from Latin costa. Doublet of coast and cuesta.
etymonline
cost (n.)
c. 1200, "price, value," from Old French cost "cost, outlay, expenditure; hardship, trouble" (12c., Modern French coût), from Vulgar Latin *costare, from Latin constare, literally "to stand at" (or with), with a wide range of figurative senses including "to cost," from an assimilated form of com "with, together" (see co-) + stare "to stand," from PIE root *sta- "to stand, make or be firm."
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 meaning "equivalent price given for a thing or service rendered, outlay of money" is from c. 1300. Cost of living is from 1889. To count the cost "consider beforehand the probable consequences" is attested by 1800.
In phrases such as at all costs there may be an influence or echo of obsolete cost (n.) "manner, way, course of action," from Old English cyst "choice, election, thing chosen." Compare late Old English alre coste "in any way, at all."
cost (v.)
"be the price of," also, in a general way, "require expenditure of a specified time or labor, or at the expense of (pain, loss, etc.)," late 14c., from Old French coster (Modern French coûter) "to cost," from cost (see cost (n.)). Related: Costing.
