The price of something is put in the ablative case.
- He sold the land for money: agrum pecūniā vendidit.
- Jokes: who wants them for a dinner: logōs rīdiculōs: quis cēnā poscit?
The ablative of price is similar to the ablative of penalty, as it is ultimately an (adverbial) ablative of material, describing the compositional means by which an exchange is achieved.
What you’ll see as often or more often than the ablative of price are similar genitive words indicating indefinite value.
- It is of great importance to me: mihi magnī interest.
- That doesn’t matter to me: illud parvī mihi rēfert.
- The cloak is worthy a great deal to me: amiculum mihi tantī est.
- I care nothing for this color: istum colōrem nīlī (or nihilī) pendō.
Common words with the genitive of value: magnī, parvī, tantī, quantī, plūris, minōris, nihilī/nīlī, assis, floccī.
(floccī is ‘of a lock of wool.’)
- I care not a straw: nōn floccī pendō.
The verbs of buying and selling:
- concilio, conciliāre, conciliāvī, conciliātus: to buy
- parō, parāre, parāvī, parātus: to buy
- redimō, redimere, redēmī, redemptus: to buy back
- vendō, vendere, vendidī, venditus: to sell
- dō, dāre, dedī, datus: to give, sell
For more on intersum and rēferō:
The Essential AG: 416-17