But second, no enterprisey company will use a service that bills like this, because
-$4 and $250 per month all rounds down to zero, so it's not a selling point
-$4 signals no support when the shit inevitably hits the fan
-$4 signals this company will tank along with your data in a month
An enterprise company with actual money will take an hour or two of dev time to boot up one of the open source registries (https://github.com/dotcloud/docker-registry) and stay in control.
Source: working at a Docker startup for almost a year
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If you are interested in the corporate market, you probably will want to offer a special 'Enterprise' pricing plan that includes 'Enterprise-y' features at a higher price point [e.g. $249 / 250 repository minimum]
Sure we're sending a signal that we're not ready for enterprise folks. I can be candid in saying that we'd rather be the digital ocean of dockers than an AWS. at this point :p