You could easily spend that much on a high performance top and bottom separately.Strafe makes one called the sickbird. I would totally get one except they are like $1,000. As someone said, be prepared for sticker shock...... If I can find a good deal, I might just get one . My wife has definitively told me she won't wear one, so I'd be wasting money if I bought her one.
I think the biggest issues (style concerns aside) are sizing and, to a somewhat lesser extent, layering flexibility. Rather than being able to mix and match size and insulation type to taste, you now have to find a single piece of clothing that both fits your entire body and is actually usable on most days. It's already hard enough to find pants that are the right waist size and length (unless you're entirely "average"). With a one piece, you not only need to do that, you also need a top that fits.