It would be nice if the pricing was such that there was a maximum, either for the price, or a configurable cap for searches.
I understand that it's implausible that I would somehow accidentally search 30,000 times and run up a huge bill, but uncapped utility billing is unavoidably somewhat scary.
I would prefer to be able to say "Once I've searched 1000 times, stop me from searching", or, as an alternate, have a system where if someone on "professional" billing searches enough to reach a bill of, say, $30 or $35, they cap out and can keep searching, but won't be billed further.