For me it rarely comes up. When it does I've already spent at least 60 minutes with my prospect and I respond with "no" and move on. Some folks are persistent and maybe, case by brief case, I pick.

Sometime I choose to give a deal to a person for my own reasons, so my one-off pay portal is used there as well.

Or one-off a client for additional money.

It took less than an hour to build, years ago, the functionally it's a one off invoice just tightly integrated with my business and optimised to two inputs. #bpaftw