Most AI chat tools price per bot, so every client you add is another subscription. The ones that do offer agency pricing are usually flow-builders with a language model bolted on. $199 a month covers unlimited agents and white label — on answers good enough to put your own logo on.
An agency's whole model is running the same playbook across many clients. Pricing that charges for each one taxes exactly that, and it caps how small a client you can profitably take on.
Flat pricing inverts it. The eleventh client costs you nothing more than the tenth, so the small retainers you would otherwise turn down become the profitable ones.
The parts that decide whether this is a service you can charge for.
That is the part agencies underrate. A bot that invents a refund policy does not embarrass the vendor — it embarrasses you, in front of the client who hired you, about their own business.
This one cites the page it read, and declines when retrieval is too weak instead of filling the gap with something plausible. Those two behaviours are why a client keeps paying the retainer after month one.
White label and unlimited client agents.