Store Attachments Offsite

I have an urgent need to store my forum attachments offsite. I anticipate probably at least 100 attachment uploads each day and I need to plan ahead where these images will be stored. They can't really be stored in wordpress because it will use up all my hosting space within a week or so. 

I had successfully used Amazon S3 before purchasing advanced attachments plugin, but now the flow has stopped. 

Does anybody have any ideas or a solution that I might be able to try?  Is this plugin unsuitable for my needs?

I urgently need to get this resolved so I can announce my forum to my group of just under 200,000 people. 

I would appreciate any suggestions.