Especially for vendors. The one aspect that's still in a bad place for consumers (and ARS pointed this out), is price. No matter what vendor you choose, the prices are significant when looking at hardware component costs.

And you can't build anything even remotely similar to a commercial NAS yourself unless you want to invest heavily in developing your own custom software. There's nothing available in the open-source space that compares (in any way) to the proprietary software on these products. So you'll in fact lose a lot more than ARS indicates by going DIY, including living with a fraction of the performance of commercial solutions and losing the ability to easily migrate disks.

Just recently, spurred by this thread, I started looking at DIY possibilities and the conclusion I came to was that nothing is quite right. The best compromise seems to be UnRaid if performance is of no concern (because it's absolutely terrible) and you can live with only a single redundant disk.

Otherwise figure on spending at least $1000 to go with Synology or ReadyNAS.