I'm not going to lie, $10k is very high for any replica unless it's a screen-used piece or something like a replica set/vehicle (or similarly size piece).
Please don't offense to this though. The biggest difference is that your piece falls almost into a grey area where it goes from not just being a "replica" but essentially a work of art given the advanced nature of how you fabricated it. So the $10k value you put on it sounds fair from a particular perspective (not a lot of people think this way, but merely take it at face-value); it's a one-of a kind piece, I don't think you're ever going to make a second one, the materials and services you rendered to get the pieces cut ain't cheap and then your labor for not just constructing it, but designing it as well.
I can certainly agree that you should make your money back and then some for the piece. While I like to collect higher-end halo replicas myself, this is way above my paygrade unfortunately. I think you're best bet would be to find higher-tier art collectors. I'm pretty sure there's a group just like that, especially for metal-based pieces. So, just being realistic for your benefit, I cannot see it being a feasible sale on OUR side of the community. It's not to say that someone won't, it's just going to be extremely difficult to find that one person who will pay you what you want out of it. You did a phenomenal job with it, and blew everyone's minds away, that's for sure, but I hope you can get what you want for it. Hell, I'd even show it off to 343i directly, and maybe you'll perk their interest in acquiring it.