Got a friend of mine that is buying pig feed in bulk for all his livestock, including the chickens. He's not got a lot of $$ to spare these days, and the feed is much cheaper than laying pellets.
His hens don't free range at all, either. It's not ideal nutrition for them, but his girls are still laying (better than he expected on the lower protein feed) and doing OK.
If you mix it 50/50 with layer pellets, it should help your feed go further, and I'd think would not cause any lasting issues for them, especially if they get some greens/free ranging time too.