Well, I have bitten the proverbial bullet, and purchased some stuff to experiment with speaker measurements.
I purchased an Expresscard SoundBlaster X-FI from Dell, for $82 incl Tax S&H. Hopefully it is a good compromise - enough quality to perform measurements, no lag or latency issues since it is plugged into a slot, not a USB/Firewire port, and less than $100.
The next purchase was $79 at Mouser. This covered 2 generic plastic boxes for creating the ARTA and LspCAD jigs, one Hammond enclsure for the Wallin preamp, and some resistors, capacitors, diodes, chassis mount banana jacks and rca jacks, and whatnot to round out the inventory I already possess.
Of course, I can't test without speakers to test with. $60 to Parts Express ($16 for S&H - yikes!) to purchase 2 Goldwood 1" Tiatnium tweeters, 2 generic 6" woofers, and 50' of 16ga speaker cable. If I get impedence and FR measurements, then I will get some xover parts for testing, and find someone to assist me in making 2 test boxes.
Over $220 just to test out a hobby. Once I build the jigs and Wallin, I will post pictures. Friggin expensive test, hope that the equipment all works. To be honest, it doesn't seem like some resistor jigs and a homemade mic & preamp will work for squat, but you never know till you try.