I've never spent any money on Halo 5 and I have around 30 snipers, 20 banshees, and 10-15 scorpions along with a lot of other power weapons. Spending money is literally just to make your collecting process go faster for the perma unlocks, but it is still ridiculously easy to get silver/gold packs. I've personally been buying silver packs (with req points, not money obviously), so when I get most of the common-rare unlocks out of the way I can actually get good things out of the gold packs.