[Avodah] early bird specials and ribbis

[Akiva Blum]

Micha wrote:
> It would seem that it such cases your chiluq would boil down to an issur
on the lashon. Writing:
    Admission: $20, $10 for early birds who sign up by Feb 15th
would be mutar, but writing:
    Admission: $10, $20 for late sign-up after Feb 15th
(or the more common, "at the door") would be assur?<<

There is more than just the lashon working here.
When you receive goods or services, that's when you actually owe money.
Until that point, any change in price cannot be considered interest on
"having my money botul with you", you don't owe anything.
So in the admission example, since you haven't received anything until you
get inside, you owe nothing however it's expressed.

Akiva