For reference, I purchased a $200k practice for .75, payable with no interest over 5 years. There was no retention provision which worried me but has turned out to be a non-factor. We've been growing over 10% per year; I've basically stopped marketing and networking to avoid growing too fast.
In 2018, two CPAs in my region just retired; they did not sell or anything. I learned when I picked up several of their clients. If I had known in advance I would have offered at least .25 and hired a tax manager for each. Each had been in business over 20 years.