Buying a for sale by owner home

Wife and I have been house hunting for a few months. Wife was at a child's birthday party for one of her friends and the friend's sister who is a casual acquaintance of my wife mentioned she is selling her home in the area we are looking. We go to see it today and it is literally exactly what we wanted.

This house is not even listed yet and they weren't planning on it for several weeks. We have been working with a buying agent for about 2 months and the guy has been great and extremely helpful. While we were looking at the home with the owners they indicated they would go for sale by owner if we wanted to to keep costs down.

We love our realtor. Want to involve him and reward him in some way for helping us search, but he had nothing to do with this house. Is there a way I can still do fsbo and maybe offer him some kind of commission to write the offer?

Still some things to be worked out. If it was fsbo sale price will likely be 310-315k. We are first time homebuyers but this falls very comfortably in our budget and is very affordable for us.