well, I would buy an amp online, in fact, I've done it several times, I just need to try out an identical amp first, to know what it sounds like, as I believe there isn't as much of a variance in quality in amps and effects.. guitars on the other hand.. well, I won't buy an acoustic online, since the wood makes up 100% of the tone, and there can be good wood and bad wood. but with an electric, the electronics make up at least 90% of the tone, with the wood taking up the other 10%.. therefore, two identical guitars don't sound all that different to me. I have bought one guitar online, my gibson, and I couldn't be more happy with it (unless it had a different bridge pickup)