When you need That Part on a Sunday afternoon, you're not going to get it from Digi-Key or Mouser.
Are you serious? It's a friggin hobby. You can wait a couple of days, hell, probably a couple of weeks without any real impact.
Sure, you can sell cables at outrageous markups, but honestly, those could be done without for a couple of nights unless you're an addict. It's very hard to compete with an online seller where the user can search, call, and/or chat with the vendor, and likely get it shipped the same or next day, with express delivery.
Retail does best when users don't know what they want, or want to be talked through their purchase (i.e., big ticket items do very well), but for people who know what they want, and don't need (or even want) to talk to someone to make a purchase, online is preferable.
I'm surprised they lasted this long - in fact, i remember seeing /. posts wondering how the hell they were making their margins with all this competitive pressure.