They work well side-by-side. If recycling made the overall per-item cost lower, businesses would have been implementing it by themselves a long time ago; paying for the recycling of every piece of plastic is more expensive than creating a new piece and then dumping it, which is why they haven't. So you can get a reduction by mandating full recycling for all plastic (new or previously recycled, of course). The important thing is making sure the producers are paying, rather than getting subsided.