MidwayUSA has Norma 7.5x55 brass in stock.
As dear ol' mom used to say, " Come and get it
'fore it crawls away!".

Here in Europe they sell FNM (Portugal) Boxer in 7,5x55.
It's much cheaper. Don't know if it is available in US. I'm not interested in their accuracy but in the cases, and these are o.k. (Norma is better though).

If in Europe you might find brass by RUAG. I understand that they supply the Swiss with their brass.