I have to agree, it is generally a bad idea. In the beginning, everything is cool, come on bro help me out, be a friend. Then if something doesn't go right, they turn on you in an instant. Well you could'a should'a...
I get this sort of thing in my work repairing furnaces all the time. People don't want to spend the money to fix it right and want to know if there's something I can do to cheaply help it to limp along. I try to oblige at times but tell them it may not last. It's cool, it's cool. If everything is ok, I'm a hero. If everything is not ok and it doesn't last then it's all, well don't you stand behind your work? lol.
Can you fix it for 20 dollars and guarantee it for life?