[Q] Screen digitizer; Broken glass topic

I drop my SP and front glass cracked, it really looks ugly. But display and touch are functioning normally. So, my problem is how to replace it. I saw screen digitizers on ebay can be bought for 25-50 USD, but I read somewhere that it's not possible to replace only digitizer but you need to replace the screen as well. Another problem is, I saw a video on yt where a man bought faulty digitizer for sp on ebay.... So, I don't know what to do?