I can share my experiences having bought three routes and sold two of my business. Both times I sold it was because I was moving.
I value a route on a three or four month earning. Three if its good but not great. Four if great, and great is that you have verifiable proof that the account is done regularly and that payment is prompt.
I set up payment as follows - 25% due on first day. I will go with the buyer and introduce to each customer and walk them through any peculiarities of a job.
At the end of the second month, 25% more is due. At the end of the third month another 25%. The final payment is the end of the fourth month and the final 25% minus the individual value of any customer they lost through no fault of theirs.
This is for a 4 month valuation. Adjust if 3 months.
This minimizes both parties risk. Included NO materials, tools or vehicles. Nor employees.
Finally - I was strict and clear on no competition clauses. This was applied only to the customers that were sold. I didn’t care if you remain in the business, but there was NO provision for the seller to ever service my customers.
Hope this might help.