I can't advise you on what to do as only you know whats best for your current financial situation. I have read all the comments and your resposnes to them and I would like to offer you help in form of Splinterland delegations. Looking at your collection it looks like you have base level summoners. I have some Beta Level two summoners that aren't being used so I'll delegate them to you with a few neutral monsters leveled to the max in which Level two Summoners allow.

Delegated Summoners

MALRIC INFERNO / Level 2
LYANNA NATURA / Level 2
ALRIC STORMBRINGER / Level 2

Delegated Monsters

Highland Archer / Level 3
Goblin Mech / Level 3
PRISMATIC ENERGY / Level 2

I will say this one thing about selling ones full collection of Splinterlands cards. I haven't met anyone that did so that was happy about their decision. The delegations will be removed at some point but they will likely stick around for a good while. Good luck on the battle field. I hope they help you earn some rewards.