Here's the verbiage I use in offers for my buyers:
ESCALATION CLAUSE (see attached addendum): Buyer purchase price to exceed that of any bona fide competing offer by $2,000 up to a price ceiling of $450,000. Proof of competing offer required for activation, please see attached addendum/worksheet for details.
Bobby Stevens
You're Home Real Estate
541-225-8081
YoureHomeRE.com