Call rst and see what they have in stock and when they expect to have what you need. Web sites are often out of date. I use them like a catalog but go shopping on the phone instead of just waiting for inventory to appear on the site.
Reloading is the way I went to get non-tox shells that were safe and double friendly. Bismuth shot was my final metal used in place of lead shot. It performs nearly as well as lead did and does not put too much extra pressure or risk of choke damage in my old, too tightly choked doubles.
It took a long time to build up my shot inventory. One very large estate find and a dozen purchases from eBay gave me a wide variety of shot sizes. Load information gathered off the internet and a couple specialized reloading guides gave me enough different safe loads for almost any need. I have loaded about two thirds of it but sadly not gotten to use it very much hunting in my old doubles. But well stored ammo will be good for years. I loaded it now while I had good selections of powder and wads for the loads that are double safe. No point saving it for later only to find out wads or powder are no longer available.
It was funny that a trap shooter bought all the leads shot for about a quarters its true value but told the widow the bismuth was worthless. She offered it to me for free. Not being a jerk I refused it unless she would let me buy it. I paid more than her late husband paid for it and happy to do so. She was both several thousand dollars richer and certain her late husbands trapshooting buddy was a moron. She almost threw the shot out. What a waste and shame that would have been.