Thought I'd post this in case anyone else was interested. I finished this before: definitely one of my favorite entries in the series for its interesting story, more naval combat, and playing as a Templar! No word on a next-gen remake or port, though with the Xbox 360 version we can cross our fingers it will be backwards-compatible down the line.
Price is currently only valid for the Xbox 360 version, but it's not too long ago that this version's clearance price was listed as $26.99:
Alternately, amazon has the Xbox 360 version for $9.99 (as of 3/9), with the the PS3 version for $10.99. Still a good price imo if you don't have gamer's club, I'll post both links below: