I only bought platinum twice during plat sales. Total spent: $40. I am currently working on my 10th level 31.

You don't have to spend a lot. I rarely spend gold or plat. I never buy blood packs, I get them free from ally missions. I have thousands of blood packs. I don't buy items that I can farm. I manage my money well, and currently have about 7m gold, and hundreds of pinks.