We have done that in Germany for a couple of seasons, I believe almost 10 in all. It was great fun, but you need about 80-120 competitors to make regionality work. When we dropped down to 50 or so, the competition died because logistics got too complicated for too many competitors. We tried various systems and the one that worked best (IMHO) went like that:
About 10 regions with about 2-3 groups in each region and 3-4 players in each group. In those groups everyone would play each other and the winner would advance. This meant that everyone had at least 2-3 matches, which made the entry fee worthwile. It was often great fun to stage "group days", where two matches would be played, so it was a mini get-together of four players. Sometimes only the winner of a group would advance, sometimes even the first two, when we had larger groups.
Anyway, we were looking to come out of the group stage with 32 players. After the group stage you would typically have 2-4 group winners from the same region and they would play each other, which left 16 players. The next round was the first, where you have to seriously travel for one match, but it was also the last. This is because the final 8 would be decided on one week-end in one central location with green fees and parts of the hotel costs paid for by the entry fees.
Oftentimes one or two of those finalists would get sick or have other duties, but it was never a problem to nominate a loser from the last knockout stage (and often a bit of a fight who could go to the finals).
Entry fee was about 10-20 quid and you get a couple of guaranteed group matches for that, which was always more than worth it in my mind.
So, in short: 100 players, group stage, entry fee and the final 8 played centrally on a week-end. There was typically a 4-6 week window for each round and the finals in September or so.
It's a very demanding system when you are just starting up. But it shows that the logistics problem can be solved.
Ulrich