You're joking right? What enterprise would install a consumer NAS in their data center to use for "data storage accessible to your web application"?
[1]: http://www.amazon.com/Synology-DiskStation-Diskless-Attached...
"In their data center" implies you're thinking large enterprises. Small businesses/industries may have requirements to keep data on-prem but without enterprise budgets.
(Your link returns 404 for me)
Couple of separate points.
First off forget "affordable". The customer that's paying for an on site version of something has a very different definition of "affordable" than whatever you're considering. Something that costs $500 literally rounds to zero.
Second, nobody, and I mean NOBODY, is going to let you plug your own box onto their network to watch some other box that you've deployed on their network. In fact, you're not going to have your app on your own box there either. The vast majority of customers will want to deploy your software on whatever version of RHEL they have a licenses for (or CentOS if they're "modern"). At best you'll deploy your app in a VM that (hopefulyy) plays nice with whatever VM kit they're using.
Third, that consumer NAS won't fit in a rack. Is it just going to be plugged in to a wall socket with a cross over cable connecting to your "app box"?
> (Your link returns 404 for me)
Sorry about that. I chopped off the rest of the gunk at the end of the URL and ended up taking too much off.