Numbers I've seen run about $7500 for the unit. Training will depend on who you buy it from, but don't skimp here. Figure a week's time at least and probably $1500 or so. With spares and such you'll want to have your total "nut" will likely be about 10 big ones.
It makes less sense, IMHO, for Nitrox than it does if you're going to dive Trimix, simply due to the gas cost for OC Trimix dives. Gas cost for OC Nitrox is trivial - I can fill a set of double 72s in my garage with Nitrox for about $5-7. Even if I BOUGHT the fills, they'd only cost me $20 or so.
Those same fills full of Trimix would run me close to $100 (including deco bottles) if I bought them, and $20 or so if I mixed my own. If I do 100 dives a year on Trimix, at $100 each I've got a $10,000 gas bill if I'm buying fills commercially. Yikes!
Deco will be accelerated on a CCR because your PO2 can be maintained where you want it all the time, which results in much shorter deco. You do have to watch O2 tox issues though - its quite possible to exceed safe O2 exposure limits (indeed, even pretty easy to do so) on CCRs.
The other problem with a CCR, which you must not ignore, is that you must have enough bailout gas with you to manage an OC ascent if the unit breaks. Having to get off the loop is rare, but if you need to and don't have the gas to do it, you die. Take that into consideration!
I STRONGLY recommend talking with some qualified instructors on the unit you are thinking of, and on rebreathers generally, before doing anything more. I've done this and while I've not yet decided to "make the jump" it has clarified the issues, expenses and benefits for me - and probably will for you too.
