There is one big advantage of plastic bags--they double as rubbish bags. So they merely replace one form of plastic with another, and this means my plastic bags contribute zero plastic to the environment that wouldn't have been contributed through plastic rubbish bags bought from the store, at my expense.
And I can think of one far worse culprit: Walmart. They import huge amounts of plastic from China, made by slaves under far worse conditions and polluting far worse per unit of plastic than my grocery bags. And this plastic becomes rubbish quickly, instead of becoming rubbish bags that displace that plastic. Walmart plastic doesn't displace anything. Not to mention all the energy wasted and pollution generated getting this stuff from China to Walmart. And, worse yet, most of this Walmart plastic junk we buy cannot be recycled--unlike plastic bottles.
Price? Plastic grocery bags--nothing (and they save money on rubbish bags). Walmart junk--too much. You save nothing--a pair of shoes from a famous company based in southeastern Maine costs me about 3 times more than a pair of plastic Walmart shoes that lasts less than 1/8 as long (and are more uncomfortable, requiring additional plastic in the form of insoles to make bearable--my expensive shoes require no insoles). In the end, by paying 3 times as much once, I am saving 8 pairs of plastic shoes from the landfill or ocean (plus the insoles, and the pollution generated getting them from China 8 times). This goes with clothing (from this same company, I get clothing that lasts multiple times what Walmart items would have lasted, for maybe double or triple the price plus less plastic in the landfill and oceans).
Yet, with all this (and Walmart pollutes the environment excessively in so many other ways that are well known--The High Cost of Low Prices documentary details this), when are they going to ban Walmart? Not to mention the abusive conditions Walmart workers must endure, that they infest whole regions and drive quality and wages, and variety, down, and they ruin whole neighborhoods bringing in the lowest classes of people to bring in their drugs and whatnot. I think I would rather keep my plastic bags that double as rubbish bags, save on rubbish bags, and keep some 80% of my stuff out of the landfills by getting longer lasting items.