The Sabaki Challenge Spirit (SCS), the Ashirara World Cup, is held at low costs. I will make an example, based on your post, RASor. (No offence intended).
1. Lucrative Purse - For the SCS, all fighters pay $100 in entry fee, and all branches pay $500. (I.e., a branch with two fighters would pay $700). This covers costs, such as lodging, the Sayonara Afterparty (

) and more. All fighters and branches pays the same, even those who live 30 minutes from the venue.
2. Sponsorship - There is a few local sponsors. One of the main sponsors is the local radio station, for example. The national sports association also covers an eventual loss.
3.
Marketing and Promotion - A letter will be sent to all branches, and that is pretty much all it takes. As stated above, the local radio station is one of the main sponsors, and runs radio spots on a daily basis to attract spectacors. But admiteddly, I believe most of the spectacors is karate affiliated people, who are there to cheer for their fellow students and friends.
4.
Venue - This might be a problem, pending on local laws. In some countries, the city hall (or whatever) is bound to with a offer suitable venue for free, or at a symbolic price. Sometimes, the national sports association covers the expenses used to rent a venue.
5.
Facilities - What items are you referring to? Gloves, tatami's etc.? These items could be stored at the hosting dojo (I believe most decent dojo's have storage rooms).
6.
Personnel - The SCS uses voulenteers only, such as other students that is not participating, parents, and other people afiliated with the hosting dojo. However, I believe judges gets a small fee from the national sports association.
7.
Fighter & Fightclub Accreditation - Please elaborate this. All fighters needs to be member of a branch, have a certain amount of experience, and needs to pass a medical check.
8.
Corporate Offices - Might be a challenge, pending on the size of the event. A website would be useful to find basic information, ruleset etc.
I believe it is possible, though it might be a challenge. But the traditional styles have done it with their WKF world championship, no? Correct me if I am wrong. It will also be a challenge to attract all Knockdown styles, seeing as there are several different rulesets. Kyokushin and Ashihara, for example, is very similar, but their rules differ (Ashihara is a bit rougher, allows throws etc.).
Osu
[EDIT: I just remembered that the
German Open is open to all Knockdown Karate styles.

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