Op, if you have to change different aspects about your idea after ever single statement then perhaps the idea wasn't well thought out to start.
Make the prices bigger, then, 25B for tier 2-3 equip, can be abused. If it was 10B each that's understandable. And the moth, it should be 1mith = 5b: Example: hits Indi, wins, gets 30 mith for one action. Sells the mith and get 150B not smart. 1 mith = 500m
About the Mith, it should only be like that if you have 6 or more. And that is way to cheap, then people would trade Mith down to little guys like ALTs as soon as they hit 5b. Would have to be more somewhere between 30b and 50b as a minimum.
This idea would be abused way too much. Mith equipment and mith shouldn't be bought, it should be earned. If you don't war don't complain about not having war equipment. Sorry but no support due to there being way too many ways to abuse this.