I guess I don't understand why you have a limited amount of vaults this a finate amount of space, and have it be able to store unlimited data for free.
Even if it is "free" then I can still turn around and sell it. If someone gave me free and unlimited Bitcoins I'd turn around and sell it on Bitstamp.
I can cut Dropbox prices in half and offer a similar service. Using the best server I can find for $30/month it can generate a monthly profit of $13,696. Sure that won't last as the market corrects, but perhaps will last longer than you think. Dropbox has gotten away with charging 100x for the past few years reselling Amazon S3.
There is nothing stopping us from also developing nodes specifically for Maidsafe with the exact same software, but Storj can continue to make a profit regardless.
Gotta diversify. there are two main reasons why MaidSafe will be able to offer free storage:
1) Data deduplication - since the vast majority of the data that is going to be stored on the network is going to be the same data (movies, music, games, books etc) it wont be necessary to store them more then n number of times (n depends on the amount of activity that data sees in the network)
2) Safecoin value - Safecoin's value is going to rise because of it's properties (anonymous, fast confirmation) and because it will be embedded as a payment mechanism in the network itself (escrow, timestamp and whatever else ends up being developed). Since Safecoin's value is going to rise the farming of the storage will be more valuable because you get the Safecoins and therefore the price of storage is going to be zero for as long as Safecoins are worth buying HDD and farming
To try to really hammer the point home for anyone that doesn't follow, imagine this - what if Bitcoin instead of using CPU's to solve complex math problems for mining, uses HDD to store data for mining(farming). Well that's Safecoin.
So instead of meaningless work with mining as a proof of work you get storage as a proof of resource.
Look if you think you can sell this and make money doing this then by all means go for it. But I think you are in for a uphill battle that doesn't make any sense on many levels. And also why build it if you know that you have a year at most before storage as a service is commoditized?
P.S. this is all hypothetical and I have no proof that MaidSafe will work as advertised. I sure hope so, but that remains to be seen