Mig welding gas

I'm just getting into welding, and I'm going to try and learn mig.

Truthfully, I haven't even attempted it yet. I've just been gathering the necessary material and this weekend I thought I had everything I needed.

Unfortunately, me being the ignorant person I am, I got an inert gas tank from a 3rd party and swapped it at my local airgas for a 100% argon tank.

Most of you probably see the problem. I haven't used any of the gas yet, and I'm hoping to be able to swap it back for the blend and pay the difference. However, if I'm unable to I wanna try and come up with some alternative options.

Option 1: I work at a brewery and was hoping our gas supplier would be willing to swap it, but I'm not sure on that.

Option 2: I'm trying to see if a gas blender is feasible, as I already own a CO2 tank. And perhaps I could use the argon tank later for tig welding and get a CO2 tank that isn't beverage grade and be all dandy in that regard.

Option 3: Just buy another tank, I like this option the least as they aren't cheap and that means the argon tank just sits there and collects dust.

Option 4: Just learn how to tig welding first.

What would you do in this scenario?