We got a crispa/sebae in that condition, a little worse probably - there was no brown only white with purple tips. We were able to nurse it back to health.
Not only is this one bleached, but very very hungry. The tents are much longer in healthy specimens.
Good lighting (which you have, but acclimate as suggested above) for the zoox., feedings because it's starving, and stability will be very helpful.
I would expect it to roll around the tank (not neccessarily walk) and probably be face down at times. We had to corral ours with rock to keep it from blowing all over the tank, only then did it begin eating and attaching. We also started out with mysis shrimp so we didn't overwhelm it with food and then after a week or two moved on to meatier/bigger foods (but not too big).
Given the TLC that it needs, and even with all of that it still may not survive, I think $25 is too much. I'm not saying don't give it a try, but that's just too much to pay for a nem that's in this condition. If they do trades, maybe you can take frags of things you have too much of in and lower the price that way.
Forgot to mention, ours was about baseball size when we got it, now it's salad to dinner plate size, we've had it for a little over 2 years now, and it's grown so much it almost has its own tank.
. In the back looks like an LTA and a BTA or healthy seabae. I would try for the LTA with your lighting. 
