Network Attached Storage Question

I have a friend with a graphic design business. They have a lot
of work that they would like to access from off site. Their first
though was to purchase a server, but with only data storage
needs I thought their money would be better spent on a good
RAID 5, network attached storage device.

Does anyone have any good advice on brands or deployment
of such a device? I'm interested in your oppinions.

Thanks
John