Musician's Friend is the mail-order arm of Guitar Center. I have used them for years for strings, as 1)their prices are OK and 2) very few stores stock the strings I like. I also bought my son a Fender Blues Junior from them - when I clicked to buy, it gave me the option of going with a Blemished unit for ~$100 less. As the kid is the sort who buys all his clothes at resale shops, I figured why not? and went for it. It was pristine - not a mark or flaw on it. I might be hesitant about buying an intrument from them, but no more than any source where I can't play it first. For things like strings, electronics, etc., where you're less likely to experience personality, if you know what you want, they are certainly a viable option.
Peter