Seller offers financing - what should I offer?

[Brendan Levesque]

I have a seller who has offered to carry some papers on a semi large (~3M) commercial portfolio. I'm not sure what I should offer.

Ideally I'd like him to carry 25-30% at 4.5%. does he laugh in my face?

Background - the deal doesn't make sense with me putting up 20%. about 7.29 cap rate, 2.88 COCR. BUT if he'll put up the 30% at less than 5.5 my COCR skyrockets.

thanks.