Pay Realtor in a FSBO Deal?

My wife and I have been working with a and have been looking at a few houses with him. However, a close family friend is selling her house. It needs a lot of repairs, but is in a nice neighborhood and has everything we are looking for. So we would like to move forward and buy it.

However... the owners are not willing to pay realtor fees for us. And we'd rather not pay $6,000 out of pocket. At the same time, we don't want to upset our realtor for not using him to help us. To add more confusion, I have an outside business relationship with the realtor we are using and don't want to ruin it.

So my questions are:

1. Do realtors ever do a "closing only" transaction where they get paid a lump sum amount to help with closing the house, filling out paperwork, etc.? If so, what is typically the amount?

2. If you are a Realtor and were in his shoes, how would something like this make you feel? Would you be angry about it? Or is this something that happens periodically and you just understand that it's a special situation and no big deal?

We haven't signed a contract with him and he has only shown us around to look at houses for one day (we saw about 6). He's answered a few questions by email, but I wouldn't say it's been a ton of work for him. Definitely some, but not a lot by realtor standards (I don't think)?

Any help you could provide would be great. Thank you so much for your time!