I think it would be $50 well spent at H&M. I myself could never make it for that price. To begin with decent oxford cloth would be at least $15 per yard, and this shirt would take at a minimum 2 yards, so there is $30 right there without any money for labor figuring out how to copy the pattern and then sew it up. This is the dilemma of the fast-fashion, cheap-labor clothing that we can purchase now.
I just thrifted my granddaughter a very cute Forever 21 dress up skirt out of some sparkly lace for $5. It has a fashion-statement zipper up the back that would cost me at least $3 to buy in a fabric store. Never mind the lace, lining and elastic components.
If you love the shirt, buy it, in other words.