How to make a purchase

It is unwise to pay too much, but it is worse to pay too little. When you pay too much you lose a little money, but when you pay too little, you sometimes lose everything, because the thing you bought is not capable of doing the job it was bought to do.
The common law of business balance prohibits paying a little and getting a lot. It cannot be done. If you deal with the lowest bidder, it is well to add something for the risk you run, and if yiou do that you have enough to buy quality.

I got this from an employer many years ago and I found out, some times the wrong way, it is quite correct.

Give me the serenity to accept the things I cannot change; the courage to change the things I can, and the wisdom to know the difference.