[smt88]

You can add an escalation clause[1].

It says that you'll pay $500k, but if they can prove they have an offer for more, you'll pay more.

There's a hard limit (you won't pay more than $X) and there's a step (meaning your bid goes up in increments of $Y).

1. https://www.thebalance.com/should-you-use-an-escalation-clau...