Specifically what kind of bike do you have? Make/model/year? Framesets (frame and fork together) are available, but there are at least a few different standards for certain parts like bottom brackets and headsets and some frames will be more compatible with your current parts than others.

Another reason for asking what particular bike you have is that some companies offer lifetime warranties on their frames. Most require you to be the original purchaser to get full coverage, but a number of companies will offer 'crash replacement' discounts to replace damaged frames.

Since you mentioned BikesDirect... They do sell some bare framesets. HERE is a carbon frame and fork on their site, although they don't have any that'll fit a 6'3" rider. Bike Island, their scratch-n-dent site, sells 'em as well.

Nashbar is another source for bare frames and framesets. Their own aluminum road frame sells for $149. (I'm not 100% sure, but if I remember correctly, it's made by Kinesis, who also makes frames for BikesDirect.)

There are plenty more sources for frames and framesets, especially if you're looking for high-end bikes. But another possibility on the budget end of the spectrum is to find a used 'donor' bikes. Used bikes, even some pretty nice ones, can often be found for less than the price of a new frame.