Symform, the cloud storage “commune” that lets enterprise customers cut costs by swapping extra local storage for cloud storage capacity, has doubled its free offering size, bringing it up to 200GB, effective Sept. 14, 2011. And by “up to,” I mean that Symform is repurposing some tricks from consumer offerings including Dropbox to get customers to that limit.

I had the chance to talk once again with Jeff O’Mara, Symform’s interim VP of Marketing, who briefed me when Symform originally launched its free storage offering. The big difference here is that when users sign up, they still get that same 100GB, as they would have before. But they get more storage space the more they help promote Symform’s platform: there’s a 10GB bounty for every successful customer referral, and users also can add 20GB straight up by getting Symform configured within 24 hours of purchase — which may be an impetus to get a Symform reseller on board to help with implementation.

To clarify, the free offering still relies on the Symform share-and-share-alike model, and users get back the storage they contribute to its overall storage cloud. O’Mara said many customers don’t even have to buy any additional drives — they’re just trying to convert their extra local storage into cloud storage that can be used for off-site disaster recovery. Anything above the free storage limit, and users enter Symform’s normal pricing tiers, which start at $10 per month for unlimited storage for three endpoints.

It’s all with an eye toward addressing the price disparity between buying, say, 2TB of local storage for less than $100 vs. what Symform claims is around $12,000 for storing the same amount with a traditional cloud storage provider. O’Mara believes cloud-based disaster recovery solutions are an absolute necessity for every company, but price is often a stumbling block.

We’ll continue to track Symform carefully, and I’d be lying if I said I’m not curious to see what the company will come up with next.