The reason you ran out of QDs is because the CP you've built does not fit the JAMMA Standard:

Games that had more than 3 buttons required an additional harness, called a kick harness due to the fact that most of the games that required the additional harness were fighters.
Anywho... onto moving forward with your project. Buy some insulated QDs, a little bit of wire, and a cheap crimper down at your auto parts store and just keep building off that daisy chain.