Opportunity to profit

Monkey menace is a big nuisance in your village. An entrepreneur and his assistant set up a shop. The owner announces $5 for every monkey brought to him.

The villagers catch few monkeys. Every monkey deposited, gets them $5. Over next few weeks, the monkey population dwindles. The owner decides to raise the price to $10 per monkey to reward the increased effort.

Over next 2 months, very few monkeys are left. Now it takes couple of days to catch even a single monkey. The cage is almost full. The owner announces his visit to the city to get a bigger cage and raises the price to $35 for every monkey once the bigger cage arrives.

In absence of the owner, few villagers strike a deal with the assistant to buy some monkeys at $15 and sell back monkey at $35 once the bigger cage arrives. The news spreads, people rush to the assistant to strike a deal before the owner returns tomorrow.

How many monkeys will you buy and at what price?