Mark, I have been interested in doing this since some of your early posts showing some of your collection. Right now I I'm in a phase of life where I need to carve out some time because I'm a bit too busy. I can picture doing this in a few years.
I had to quit brewing for several years due to demands on my time, so I know what you are up against.
With that said, once you get setup and start maintaining your own bank on slant, you will kick yourself for not doing it sooner. The basic skills necessary to prepare absolutely sterile media and plate/slant yeast are high school-level biology.
I was basically in the same situation that you are today when I first started to maintain a yeast bank. At that point in time, anything other canned kits, questionable dry yeast, and oxidized hops was considered to be exotic. White Labs did not exist, and the Wyeast catalog could be enumerated using two hands. Many Wyeast strains were difficult to obtain due to the perishable nature of liquid yeast and the relative immaturity of the market.
With that said, things changed rapidly after 1993. However, the impetus for that change was not the AHA. The driving force behind the rapid technological advancement within the hobby was a magazine called Brewing Techniques (compare Zymurgy articles from the same period with those published in Brewing Techniques, and you will see what I mean). I did not bother to join the AHA during my first pass through the hobby because I did not care for Zymurgy (I still only scan the magazine). While the quality of the articles in Zymurgy has improved greatly over the years, it's still more of an entry level/brewing lifestyle magazine than a true nuts and bolts small-scale brewing magazine. The community needs a modern version of Brewing Techniques. Neither BYO nor Zymurgy fills the void that was created when the publisher of Brewing Techniques shuttered its doors. In my humble opinion, the BA/AHA should consider offering a subscription above and beyond the cost of membership technical journal much in the way that the Amateur Radio Relay League (ARRL) offers QEX (the ARRL's lifestyle magazine is called QST). I would write for such a journal.