Wiki: https://wiki.musicbrainz.org/User:Freso/BandcampRelationship
RFC: http://lists.musicbrainz.org/pipermail/musicbrainz-style/2013-November/019517.html

We do have a bunch of Bandcamp URLs in the system already, however, it bothers me that every time I go to add a Bandcamp URL relationship on the Artist or Label level, it's either "can be purchased for mail order", "can be purchased for download at", "can be downloaded for free", or "can be streamed at". A lot of Bandcamp sites allow for several of these options, and all allow for streaming. It's not uncommon for hip hop artists to have some releases available for free, some available to purchase for download, and a few you can get e.g. an LP version of (mail-order). I feel it would be better to have a "Bandcamp" relationship, rather than having to figure out which of these four (well, streaming + which of the three others are relevant) would be proper for the given Artist/Label.

Note that I'm not suggesting this on a Release or Recording level: I think it is fine to stick to the more specific types of "get music at" relationships for these, as the entities themselves are more specific towards the music that someone might want to get.

I would suggest this to be a child of the "get music at" relationship, like the four relationships that are currently used for Bandcamp URLs.