just rescued this guy from one of those chain stores

[Coluber42]

Overhead dictates a lot of cost. Many people don't know or forget what is costs just to open the doors.

Retail is expensive, especially brick and mortar retail. Typical retail markup is 100% - in other words, the store sells the item for twice what they paid for it (or the distributor gives their retailers a 50%discount off the retail price, which is the same thing). But they aren't out to rip you off - most retail store owners are not rolling in it. And that is for inanimate products that don't need to be fed, cleaned, watered, quarantined, etc.
Maintaining a store that people can walk into and buy things requires paying for square footage in an area where people go to shop, and employees, and a good selection of stock, etc. Paying $100 for a normal that's healthy and well cared for, from a store that takes good care of their animals isn't so ridiculous even if you could get one for $20 from a breeder; you aren't paying the extra $80 for the snake per se. You're paying the extra for the convenience of being able to walk in off the street and buy the snake in person on the spot; and pick up your bedding and feeders and other stuff in the same place, and the instant gratification of having your purchases in hand right away.

If that's not worth the premium price to you, don't shop at a pet store. But don't expect the convenience/service of a brick and mortar store for the price of someplace with minimal overhead.