Personal opinion: no thanks.
ODP is, by its very nature, a give back to the Internet and the people who use it. Any form of contribution/donatoin, etc. no matter how worthy, tarnishes the entire thing.
People don't read. It would take about 4 nanoseconds before the first clueless individual went onto (pick a website) and complained tha tthey paid their $5 and didn't get listed, and what a bunch of thieves we all are. Then the "intentionally clueless" would jump on this as "proof" of (pick a stupid subject).
No one will take me seriously, but I personally like my my idea for getting rid of spam: turn off submissions until such time as there are no unreviewed sites, then - without notice or fanfare - open them up until "n" sites are submitted, and then close them off again. Stir well and repeat as necessary.