Hector - Are you buying this as a collector's putter or something you can use? As a collector, the Mercedes putters are quite plentiful, and that keeps the price down. About 4 to 6 months ago there were a bunch on eBay and they were sometimes selling for less than $100. Since then the price has rebounded, and I've seen a bunch sell for more than $150, sometimes over $200.
If you want a Bettinardi to use at a good price, and you like the style, go for it. Keep in mind though that the X material the Mercedes is made of (as well as any Hogan Bettinardi with an X in it) is very, very soft and it dings and scratches easily. However, as a wall hanger it looks great. If you use it, you can still keep it in good shape but you have to be careful.