If you can convince an ISP with a similar service or even a service relating to what you want I am sure you can get it done. As for buying more drives, no its not more viable. You will always need (N + 1) and if you cant separate location with included symmetry of data your still looking at a loss. If this is your bread and butter then its wise to actually call/email ISP or even challenge 1 or 2. They all claim to be the best in the market and this is not exactly some unknown tech...
Just saying, why dont we as consumers refer all these businesses to a source of innovation. Look at Google, Amazon and the like. They innovate to make profit--no-one cared about Google-Drive or Dropbox until they actually saw the importance of random access from anywhere.
All I am saying is, we are just paying for the same old **** at a higher rate locally... but we get practically 0 innovation. A pretty website here and there to autodeploy puppet/chef recipes into a vps "cloud"--with the level of support you would get from a adsl tech who installed virtualbox on his windows xp desktop.
Sorry for my rant... I'm Just Disappoint...
In the end here is (A) solution:
Step by Step:
1: Contact an ISP.
2 Do they run a dropbox or the like system. Owncloud is the current #1 for opensource.
3: Is this service running on a JBOD server cluster
4: What is the server eco system like:
4.a: The File System. If they say ZFS then its a +1!
4.b: The transfer rates to and from the servers to clients. If its a case of how fast you can get there then ask if you can install FIBRE or a wireless link. Overkill but still worth asking.
4.c: The redundancy configuration. This includes not just RAID or RAIDZ but also entire server redundancy i.e.: TCPRAID
4.d: D.R Time. Should disaster occur at their DC, what is the maximum expected disaster recovery time.
5. Over all cost on a p/GIG base.
6. Cost for bandwidth charges
7. Alternate arrangements for sending external drives to DC location for upload. (This is only in your case since one can assume you would do large shoots from time to time resulting in 100's of gigs of data, if not then excuse the assumption)
None of this is rocket science... It just takes a little brainstorming and someone willing to listen and think about the problem.
PS: If i missed a few things... excuse me i'm groggy before my morning smoke
