He that sells upon trust, loses many friends, and always wants money
He who buys had need have 100 Eyes, but one's enough for him that sells the Stuff.
Buy what thou hast no need of and ere long thou shalt sell thy necessaries
Again, He that sells upon Credit, asks a Price for what he sells, equivalent to the Principal and Interest of his Money for the Time he is like to be kept out of it: therefore
To whom thy secret thou dost tell, To him thy freedom thou dost sell
Nothing's so apt to undermine your confidence in a product as knowing that the commercial selling it has been approved by the company that makes it.