Slowhand, go look at Taylors website, they had the Uberti 76 on sale in under the clearance tab.
Also as to powder you'll probably be the best off by ordering some KIK 1.5 from Powder Inc. 10lbs is 156$ delivered to your door.
I've not done anything with the 45-75, but unless its more of a bugger to work with than the 44-77, the stuff about these bottlenecked cartridges being hard to work with isn't necessarrily right.
Forgot to add if you have a spirit of adventure CDNN investments has Chapparrels for about 600$.
And yes Jamison did close their doors , but that brass is in good supply at both Buffalo Arms and Grafs.