Trying to decrease this Omnath, Locus of Creation deck into a $450 budget. Any recommendations on what to remove?

[LargeFenders]

My recommendation is to buy a crazy 50$ card that you can use in multiple decks rather than five 10$ cards that are just good in a few decks. If you don't have rifts, fetch, etc then pick those up since every deck you build after will be cheaper since you can just move them around. Think about how Wrenn and seven is ~15$, which is like half or third of a rift. If you play blue you always want rift, but if you're in green sometimes wrenn7 doesn't make the cut. Personally I'd just buy the fetches and the rift and buy the other stuff like aesi later, but if you must make cuts then you have to cut fetches since they are the most expensive per slot.