I see it regularly sell on ebay for around 125 to 150.
Strange for $100 thou at EB/BS. A local EB had one a little while back (may still have it) and only wanted $50 for it (controller, game, manual, case, but no ammo cardboard box). Some of the paint on the surface was a bit worn (near the left throttle and around a couple of more often used buttons) so I passed, as I would rather have one is good shape (that way if I wanted to part with it on ebay I would have a better chance of selling one in good condition).
One local movie/game store (not EB/GS) has had them and sells em for around $100 too. There is another store, but I'm not sure how much they charge for em (need to check next time I go by there).
"is it worth it", I think it's a toss up. I was interested in picking one up (and may still do so "some day"), but, it's definitely one of those harder core items for Mech game fans. From what I've seen, the game is slower paced (think Chrome Hounds as opposed to Mech Assault or even GunGriffon). Due to the large amount of screen taken up by the inside view of your mech, the actual view space for gameplay is a bit less. Keep in mind that multiplayer requires System Link (one setup for each XBOX), or, the Line of Sight sequal/expansion for Live play (if anyone is still playing the game online).
Oh, be sure if you are playing the game, do NOT shut off your XBOX until a mission is finished/saved/etc. If you do, the game ERASES your save (just like if you die in the game, you gotta start ALL over...yeah, it's a hardcore game that way).
Now, as all of that sounds sorta "meh", there definitely is a COOL factor associated with a 40 button HUGE desktop mech controller and pedals used to operate the game.
*****
I'm planning on eventually picking up several original XBOX consoles and using System Link to hook them together so we (as a family) can play some of the cool games that support System Link gameplay. And, even if I eventually do this, I doubt there would ever be a chance to run across that many Steel Battalion setups...lol. :}~~~