Only one problem with the screen grab method, Jack - I don't upload anything to my FA account unless it's ready for sale. Our portfolios are meant to showcase our best work, and having a section marked 'experiments' or 'for forum use only' or whatever (even if it's password-protected) doesn't look very professional, imho.
As far as discussions are concerned, it's easy enough, if a bit time-consuming, to display a tote bag image with a link to the relevant sale page, but of course that doesn't work for groups or competitions.
Image don't have to be huge, by the way, just add height and width to the code to make them a manageable size.