I needed another powder measure for my 650 & could not find any place on the internet who wasn't in backorder. But, I did find that many do have the 1050 powder measure in stock. I had recently found out that the only difference in these is that the 1050 comes with a heat treated die & costs about $5 additional = $94.95.
Ben Stoeger Pro Shop had them in stock, as well as a couple of other goodies I wanted - UniqueTek powder baffle ($10), & the quick release for the measure ($26). He assured me they would ship next day at the latest.
Anyway, if you need a powder measure for your 550, 650, 750, if you don't want to wait for a backorder, & if you don't mind paying an extra $5 for the heat-treated die, you can probably buy the 1050 measure many places. I got mine https://benstoegerproshop.com/