How difficult and expensive to repair the cracked glass screen

I have newly purchased an aluminum AW4, but when I took it off from my wrist it accidentally fell on the hard ground surface facing down, so the glass cover cracked (I didn’t expect it to be so fragile). Apple Store asks me $349 to replace it with a new one, which I think is to expensive (65% of the retail price!). Therefore, I’m begging help on the ifixit.com, hoping to get a guide and quote or just a general idea on how difficult and expensive it is to repair by myself. I am an engineer, and have experience replacing the home button of iPhone 4, so I’m pretty confident about handling small things. But I don’t have any experience in handling the water resistive seal or to use heater to melt the adhesive. It’s not hurry because I can wear it as is since the capacitive touching and Force Touch functionality are both working right now. And also maybe it will take a while until the 44mm replacement screen be available. Any suggestion would help, thanks!