Firstcall in the U.K. sell these bags but only full of chemical . If you are asking where you can buy empty bags to allow you to fill them yourself then I don't know and I suspect you are asking this. I think these bags are made specifically for certain makers who sell the developer/fixer etc on these bags and you may not be able to buy a few of them as a member of the public.
However why not buy 3L wineboxes, drink the wine then re-use the bags. I do this all the time. Eventually the taps for pouring will leak but by then the winebag itself should probably be replaced.
So unfortunately you have to buy more wine and drink it. A dirty job, as they say, but someone has got to do it