While it is possible to "buy a slot", the usual way is as explained above, by competing in regional qualifiers. HQ distributes the slots proportional to the activity in member clubs. In my geographical area (Section), there is a Championship Series, with each club in the Section hosting one match that is scored as part of the Series. One club also hosts a Section Championship match in conjunction with their Series match that counts as two Series matches, and the individuals who win the Series Championship in each competitive division are guaranteed a slot if they want it. In '08, the champ didn't want his slot, so I'm going. I won the series this year and probably won't go to nationals again next year, so the guy who finished second will probably have a "shot" at the slot. Slots that are allotted to the clubs and Sections for distribution are often returned, and those become at-large slots that can be bought through participation in a sort of first-come/first-served online competition alluded to above.