Your budget won't support a top artist and an experienced programmer for more than a month, if that.
Ideas aren't just cheap, they are worthless. I'm sure you don't honestly think that you've come up with something radically new, so that just leaves us with incremental "It's like this but with a bit of that" that the entire industry thrives on. Nobody will steal your melange - every person reading this will have their own ideal project and would much prefer to do that, given the chance.
However if you're not leading the programming or art, this is will never get off the ground in the first place. Game designers as a separate entity are pretty sparse in large companies, but in indie land you have to be able to bring more to the table. All of the artists or coders here also double as game designers etc. You could carry it off on a large project, but not one of this scope without a budget.