Depending on your situation I would suggest getting into the reloading business. The startup cost will be high but having a reliable supply of ammunition for the fine cartridge will pay for itself. At $80 a box it will not take too long for the equipment to pay for itself. Just an opinion but the investment in reloading equipment will pay higher dividends.
A brother has the pair the 308 Norma Magnum on a Mark X action and a 358 Norma Magnum. I believe he uses .338 Winchester and 300 Winchester cases to create cases for his 308 Norma Magnum.
There is a lot data for the 308 Norma Magnum... A quick look at my latest Hornady Manual shows it still in there and liking slow burning powders.
A small sample of data from the Hodgdon site for the 308 Norma Magnum.
180 GR. HDY SP Hodgdon H1000 .308" 3.345" 72.0 2769 45,900 CUP 76.0 2940 51,900 CUP
180 GR. HDY SP Hodgdon H4831 .308" 3.345" 67.0 2865 43,200 CUP 73.0 3022 52,300 CUP
180 GR. HDY SP Hodgdon H4350 .308" 3.345" 65.0 2770 43,000 CUP 69.0 2999 52,800 CUP
180 GR. HDY SP Hodgdon H414 .308" 3.345" 58.0 2772 50,500 CUP 63.0 2908 54,300 CUP
180 GR. HDY SP Hodgdon H380 .308" 3.345" 58.0 2746 48,600 CUP 63.0 2847 51,400 CUP
180 GR. HDY SP Hodgdon H4895 .308" 3.345" 54.0 2732 48,200 CUP 59.0 2898 53,400 CUP
190 GR. HDY BTSP Hodgdon H1000 .308" 3.435" 70.0 2711 45,500 CUP 74.0 2891 51,100 CUP
200 GR. NOS PART Hodgdon H1000 .308" 3.400" 69.0 2674 47,400 CUP 73.0 2859 54,500 CUP
Link to the site and follow the menu.
http://www.hodgdon.com/basic-manual-inquiry.html