after my first mac (95) I have bought mine off of eBay... I've been happy with them and they've served me well... yes, watch out for scammers...I usually review the seller ratings... if anyone has too many unfounded/unexplained negatives, I go on to another seller... there is a seller I just bought from and he offers a 30 day warranty... he apparently refurbishes the machines and usually has a wide selection of G3s...the beige G3 I just got for my wife was clean, extremely well-packaged and he'd even installed a couple of additional parts I'd bought off him...
the seller's eBay name is rwwilson, I just checked and right now he's off on vacation and not back until after the 28th...