That doesn't sound right $170 for 5 pumps comes out to $34 each pump. with ss head! I'll tell you what, if that's the case, I'll buy all 5 pumps from you for a total of $340.
The plastic-headed pumps are usually in the $140 range but if you're lucky you can score them for a little less than that. I've never seen the prices for the ss head so I don't know if $170 is a great deal, but it's not bad.