I am assuming you are looking at the TaylorMade Ghost Manta Putter Level 30+ and the TaylorMade Ghost Spider Putter Level 35+. You didn't specify, but these two have matching stats and the price difference is 495c.
When I see something like this, I tend to defer to the one with the higher Level rating, in this case, the Spider putter, figuring...hoping...anticipating that maybe WGT has given it a sleight edge somewhere that doesn't show up in the stats. Who knows, maybe it's just my imagination.
If you are leaning towards that price range, then why not consider the Daytona Putter 2011 (L55+) Do a comparison between the two and you'll see that the Daytona comes out on top.