Only when genuine interest on the part of the competitor has been established can your company's name safely be divulged. A customer who purchases a product from you and then resells it is another potential buyer. Buying your company may offer that customer new business opportunities in an area he or she already understands. However, if you have multiple customers who compete with each other, you'll want to exercise extreme caution approaching one of them. Again, consider hiring a third party to sound out interest.
Vendors are good prospects for much the same reason as customers.
Purchasing your business represents an expansion into a known area. This is particularly true if you've been a customer of theirs for some time and have an established sales record. Some of the best prospects may be right under your own business roof-partners and employees. If you've been running the business with others, those people are likely candidates to take over. Especially in small businesses, you'll find long-term employees who have learned your business inside and out.