Crank Pulley

[sujeemax]

My crank pulley just broke and i have to fix it. The dealer is asking for $194 and 1stsubaruparts.com is asking for $139. Then i found some pulleys on eBay on the link below.

http://search.ebay.com/svx-pulley_W0...ageNameZRC0022

they are lot cheaper but i would like to know:
Is under drive crank pulley and crank pulley the same?
Would you recommend me putting these pulleys on my car if they are the same?
Is it easy to install? because there are some angle marking on the top?
Does anyone hove one for sale?

Thanks
Max