Looking to Buy (santa rosa)

Hello.
.
.
I am a senior and going to be raising my grandson.
I want to buy a 2 bedroom condo, older small house ok.
I have a very small down payment, maybe 20% of $300,000.
I would qualify for the payment on $150,000 so the seller would have to carry a second.
I was a home owner, now rent and have good references and good credit.
I need to stay in Santa Rosa area.
Thanks.