We tend to do one massage on our cruises. $100 is about right. It depends on the type (hot stone, aroma therapy etc...) but the standard swedish massage runs about $100. Is it worth it? I guess so... the wife gets them locally for about half to three quarters that rate, so the price isn't completely out of bed. Watch the caper paper for specials (normally on port days) and you can get it cheaper.
Just watch the 'sales pitch'. or you'll end up coming out of your massage with $200 in worthless lotions and oils that have all kinds of healing powers. Some of which you will be amazed to find out that you should already be cripped from not having been using them... (Ok, that's a bit of an over statement.. but that's what it seems like.)
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007, Celebrity Silhouette 2013