Is it cheaper to fix screen on my Samsung Galaxy S6 Edge and get a new battery in it or just buy an S7 from eBay for $220?

So I need some advice on phones. I currently have a Samsung Galaxy S6 Edge and I ve had it for about three and a half years now. I love it and it still runs good. The battery life is so so as I have had it for three and a half, the screen is cracked and it is a little laggy sometimes but there is no really serious problems with it. I am looking to fix the screen which has some cracks but not too many. On the top there is a lot of cracks on the bottom as well as the camera and just above the camera on the back. I m also looking to get a new battery in it so that it lasts me another couple years and to just have the convenience of not having my phone die every 2 hours. I m asking is It cheaper to Simply fix the screen and get a new battery in it which is an edge so I assume that it cost more than just a normal phone. Is it cheaper to just do that or should I just buy an S7 unlocked from eBay for 200 some dollars? I m not going to make this decision for at least another few months but would appreciate feedback. Thank you.