Telemarketing Sellers

I telemarket to find my sellers,
I basically have a script I use first off but when I get to the question whats your asking price when they dont have one how should I handle that? I have access to the assessed value should I somehow use that in determining how much to offer if so how much below?
or should I tell them i’ll get back with an offer and if so what reason do I give for needing time to make my offer?