Since the 7mm-08 uses the same brass as the 308, ........
Maybe not the same brass, but the same equipment is used to make it as all the other .308 based cases ...... and that's being used to capacity making the more popular .308 and .243, maybe?
It's an economy of scale thing, I think: Prices for .260 Rem were really outrageous in these parts when I was looking at buying one a couple years back...... and not just because not as many were produced. On the other end, Bass Pro/Cabela's/Scheels only sold a very few boxes a year compared to .308, yet a box of .260 took up the same width of shelf space as the more mobile caliber ....so of course they had to charge more to make it pay.....
Learn to handload. Then you can form brass and make what you want.