Cheapest way to run Oculus Rift CV1 on MacBook Pro 2015 15" (dedicated graphics)

Hi,

I recently got an Oculus Rift CV1. I understand I can't run the Rift on my current graphics card (AMD Radeon R9 M370X) because it's a mobile GPU, but I was wondering what is the cheapest way that I could run the Rift on my current setup (MBP 2015 15" 16GB RAM, 2.5GHz Intel Core i7, and AMD Radeon R9 M370X). I have Windows 10 installed and when I tried to run the Oculus setup software it told me that I needed to update my AMD driver. Although when I tried to update the driver it said that I don't have compatible AMD hardware. I looked around the internet and I found out that I could setup an external graphics card to my mac. What it the cheapest way I could run the Rift on my mac?

Thanks in advance,

Eric