There are ebay hubs for damn near nothing. Shaft and spline on the B13/B14 (and probably B15) are the same as a S13, so search for that and you'll find hundreds of the things.
They are, by the way, complete crap. Poorly cast pot-metal crap that is highly susceptible to cracking.
To get back to the original question, the original NRG "thin" Quick-Releases are supposed to be pretty bad (lots of play), but the larger ones are generally well thought of. Since most aftermarket wheels have a lot less dish than a stock wheel, having a thicker Q/R probably isn't a bad thing.