Somewhat, but I think 129.99 for 250GB Xbox 360 Hard drive is fair since it uses a 2.5" laptop hard drive which are more expensive then a 3.5" desktop hard drive. Plus, it is an extenal hard drive which requires a protective shell and other cables and circuit boards in most cases unless it uses E-Sata. Plus, MS needs to make some money.
A 2.5" 250GB USB external hard drives made by a good company like WD, Lacie, Toshiba, Hitachi cost $70-$100 at most offline stores since you have to pay for the 2.5" laptop hard drive, protective case, circuit board to convert SATA to USB, and USB cable.
I find it kind of strange when people compare 3.5" internal hard drive (drives meant for desktops) prices to the Xbox 360 hard drive prices.
I predict the next Xbox hard drive size will probably be 500GB or 1 TB. I still find it a better deal then those Xbox 360 Memory cards which only holds 256-512MB and cost 20-30 bucks depending on the store.
I heard if you can use a regular 2.5" SATA hard drive formatted in FAT32 and put it in the 360's hard drive enclousure for the 20 or 60GB version, but you risk being banned from Live and voiding your warranty for modding and using 3rd party items in the 360. But, if you just use your 360 for non-online stuff then you are okay since you won't be using live.
It really is a bit pricey, but you got to pay more for a little more luxury, right? I doubt they'll make a TB harddrive anytime soon, but a 500 GB is viable.