Separating the product (D7) from the service (support) makes a lot of sense.

$20/month for support, to me, is not unreasonable, provided I get the agreed level of service with that (ie it REALLY delivers). At the end of the day, if it's support that truly gets me out of potholes and it's reliable, then the cost-benefit equation easily tips to the 'benefit' side.

And that's just for one site. But since I intend to run a few D-powered sites, my support cost per site will be truly low.