GSA is going to be your most cost-effective solution. Or ZP maybe, but GSA will work out of the box, whereas you will need to script ZP to post to them. You could also use SickSubmitter with a custom premium packet or you could use Licorne AIO. There's probably other software around that posts there too, but as mentioned already, scrapebox does not. However you can use Scrapebox to find buddypress URL's to feed the software.