I'm 6'9", with very long legs. Invariably, whenever I enter a bike shop, I am greeted with "you need a custom bike." This is very annoying, because my bike is less than 3 months old, and it seemed fairly expensive for me, yet very, very cheap compared to a custom bike with decent components. And, honestly, who'd put tiagra on a custom frame? I think Ultegra or Chorus would be the minimum.

My personal view is that it's better for me to get out on a bike, without necessarily fitting perfectly, than waiting until I can afford a custom frame (which would be quite some time from now). And yet I can't avoid the custom frame pitch.

What do other people feel about this? Is fit really that important an issue? I'm young and poor, and haven't really ever fit on a bike properly since I was in 6th grade, so I've never felt a "perfect" fit.

Fit is important. BUT, you are young and flexible so you can deal with suboptimal fit. As you get older, this will get harder. Even now, a custom fitted bike will be more efficient and more comfortable.

As far as custom frames go, you needn't spend the kind of money Waterford, Calfee, Bob Brown or Rivendell command to get a nice custom frame. Gunnars can be custom built for around a grand and Mercian and Bob Jackson in the UK can do it for even less. Still, it's more than a lot of off-the-rack bikes, but it's also cheaper than a lot of other ones. And really, who cares what components you put on it? Buy a bike to ride and fit your budget... not someone's preconceived notion about how it should be equipped.

All that said, ride what you have until it doesn't work for you any more. Just make sure you know what your options are when that time comes.

At least for me bad fit lead to recurrence of my knee problem. I have a prety "standard" build so I could get away just paying for a fitting for my current stock bike.
I bet knee surgery is much more expensive then getting a bike that fits you.

I would look closely at Leonard Zinn. A former college roommate of mine just took delivery on one and loves it. He's tall and has been through MANY road bikes through the years - custom and stock. He says he never thought he'd ever find a bike that would fit him as well as it does. So, when you finally have the reserves to do it, look into Zinn.