What I do sometimes for both instagram and twitter is, using my AW site, create a frame around the image and then take a screen shot. Using my image organizer (Acdsee) I add the web address to the database. This only has to be done once for each image, it's then easy to share, using hootsuite, to twitter, instagram and facebook in one go. Being a fairly small image, around 500 pix wide its unlikely to get copied but its big enough to encourage potential customers to click through (on twitter and fb )
One of the problems with instagram, I don't think links in the comments are clickable.