This is how I feel about "reasonable" prices. Anything is worth what YOU are willing to pay for it. That goes for cars, houses, clothes, animals, etc. What one person wouldn't pay $25 for may be worth $100 to someone else.
$125 for 3 chins is cheap, generally speaking. But what about their background? Do you know anything about that?
There are so many variables here, there's no way anyone could tell you if you're getting a good deal. If there's a history of malo or something, you may be getting off cheap now, only to have a lot of time, money, and energy, and heartbreak later spent on caring for unhealthy animals.