gspec, I'm not sure what the difference in bolting mods on at home in your own shed and having a mechanic do it..
yes people do, do dodgy mods but if mods are done properly why can someone do them at home ffs. i don't have thousands to spend every time my car needs maintance, id perfur to do everything myself so that i know that its been done properly. or if something is on the way out and i have not been able to replace it, I'm well aware of the problem.
i do agree with the other things you have said though. a lot of dodgy examples that seem to be over priced, sometimes you just need to sit back and have a chuckle to yourself because the seller is wondering why its not selling. but then again, if you want to sell something quick then you would tend to put a lower price on it, if I'm not really fussed on selling something then i put a higher price on it.