It may take years before his daughter owns it. If you'd like to try to buy it now, then here's what I'd do:
1. Pay an appraiser ~$500 to determine an opinion of value. Ask the appraiser how he or she accounts for physical condition. You can get two opinions and take the average of the two. It'd take the guess work out of it. You can use that number to negotiate with the seller.
2. The seller seems to already understand that what he keeps is more important than what he grosses in the sale. Remind him that he'd save 5% off the sales price by selling directly to you and bypassing brokerage fees.
3. Go the next step and try to work out a seller-financing agreement that works for both of you (check with an attorney). For him, he'd spread out his capital gains over multiple years and would probably pay less taxes (check with a CPA). You can explain how it can be like supplemental retirement income that he'd get by the month. For you, you can use the 30-year conventional mortgage interest rates of ~2.75% as a benchmark for what the interest rates should be for the seller financing agreement. You can also explain that you're open to refinancing out of it with a conventional bank loan if he wants the income sooner for any reason.
I've never done seller financing before and am neither an attorney or tax accountant. I'm just a local in Oakland (30+ years) and am an active agent and investor (rentals and flips). These are my two cents for what it's worth.