Steam Machine or custom PC for the same price?

I read many times that SM´s HW is not future proof and its not ready for great VR experience, and as I have an old PC (i5-7500, GTX1080 8GB, 16GB RAM), I could invest in modernizing this PC but the max specs I could achieve (i7-7700, RX6750XT) would be not competetive.

So I was thinking, how much more money I would need to invest to get a stronger PC that can VR than the SM? Lets say whatever price is the SM going to be, thats the max I´m willing to pay for a PC. I can reduce my expectations on graphics quality and performance, but for the same price, can I build a stronger PC (strictly on AMD GPU)?