Off the top of my head not 100% sure... But like $650-800 BNIB, used can be had for like $500-600. Boxes anywhere from 6ft3 - 10ft3, all power dependent. Tuning they like 32-36hz, in my experience with Solos anything over 40hz is gonna be terrible for daily.
They are louder than BTLs + 9518s off 3500 watts, before the flame there is testing that we've done to prove it. Over a 1.5yr period a teammate had all 3 woofers off a Sundown 3000D @ .5ohms. They were all in optimum daily boxes and as far as burp/bassrace scores the Solo-X was the loudest by over 1db burp score/.7 or so bassrace. They were all prolli the same in handling the power for multiple full tilt songs and demos. The new cones are definitely alot stronger than the old gray ones were though.