Many buyers want the vendor to provide vendor take back financing. The buyer is trying to minimize their risk and wants to ensure that the vendor encourages customers to stay with the business. If the seller has several large customers whose sales exceed 50% of the total revenue of the company, the longevity of the company is economically dependent on 1 or 2 customers. If one or both leave, there is nothing left of the company. In these situations, the buyer wants the vendor to assume part of the risk, The vendor gets paid as long as the customer stays. There is a lump sum payment in advance and the rest is paid out over 1 to 3 years, depending on your negotiations
If the vendor provided a vendor take back financing, they need to ensure that they are able to monitor the business operations. If the vendor has no access to the accounting records, he will not know that the company has lost a customer until the company can no longer pay the take back financing. If the vendor is asked to help, the seller has a vested interested in helping the buyer.
I also find that many companies will offer a VTB when they are at a difficult price point to finance. I have found that companies for sale between $300,000 and $1 million are difficult to sell. They may be too big for a small buyer, he will not be able to borrow enough money from his home or other assets to buy the company and the company is too small for larger investors. In these situations, you need to cater to the smaller buyer and provide them assistance so that they can buy your business.