Hello,
ok so what's the strategy here exactly? I see a lot of mana-generating creatures and Myr sphere as a huge threat with myr synergy, but I feel something is missing. I'm aware it's supposed to be a budget casual deck but I would suggest to think about some addition to the deck- either some kind of articact or mana-expensive spell that can change the situation on the table. Maybe something like
Steel Hellkite? Or
Tempered steel? OR some multicolored spell?
Hand of Emrakul? Try combining it with a card utilizing this mana in a most efficient way, either with some ability or triggered effect.
Or some card that could bring an artifact form the grave to the battlefield. Myr decks can be cheap and pretty fun at the same time, so just give it some thought and give it a try ^.^ Or don't change anything, f**k it. Have fun.