I have also sold items; both of value and of less significant value, where I was offered much more almost a blink later and would never lose face in backing out on my word.
A reputation is priceless and costs highly to build - especially in business. It can take a lifetime to make and a second to break!!! One false move and you are then on borrowed time!!!!Selling your reputation for a few thousand dollars can end up costing astronomically more in lost business and lost trust in the long run. Has one ever wondered why some big companies take out sponsorship of various sports and other institutions. It is a form of advertisement and buying their reputation. One can say that it is exactly buying a reputation so that consumers can learn and trust your merchandise. Above all your word and honour!!!!