Buy a new latest-and-the-greatest (sport or cruiser) Jap bike for $8,000-12,000 and in 1 year its a has-been and you'd be lucky to get half that. Sorry, thats not for me.
Buy a classic SOHC CB750, put some time and money into restoring it, you own a great rider, take pride in it, put it in bike shows, garner complements everywhere it goes, and its almost always worth more than you got in it. Plus you get to mess around with an icon. CB750's will NEVER be over-rated.
Ebay a double-edged sword; good parts prices are sometimes up but if your selling thats obviously not a bad thing. Bargains are always to be had if you dig. Think outside the box when searching.
You know, only 8 years ago or so, before internet got popular the only way to get parts was thru magazines, many phone calls to junkyards, mail-order funds, things bought sight-unseen w/o pictures and process took months.