Regardless of wether Everton value Coleman highly or not we have the money to get him. If it means spending a bit more like 15-20m it's better to spend that and get a guy in who is probably one of the better right backs available at the right age and will slot in seamlessly. Worse options would be-
1) Buy an inexperienced right back with potential like Aurier and have him compete with Jenkinson
2) Buy a value right back and spend similar money replacing him when he turns out to be crap like Santos.
3) Promote Jenkinson and have bellerin as the reserve right back. The very worst option.