Thanks Martin I was wondering more specifically if one was stainless and the other was brass but if the units themselves are the same my order is going in today.
I only got the $16.95 one so i can only speak for that one but:
The tank sleeve and the cap seems to be chromed brass and both the base and the mid part including hardware and center post/pin (to which the screws and all the hardware attaches) are stainless per the magnet test.