Pier construction, materials: Alum vs Steel, etc.

This may be a stupid question.. I don't know but..

If I wanted to have a pier made that will support a 10" LX200 and associated gear for observing as well as CCD imaging.. what are the plusses/minuses of the following metals? Aluminum, Steel, Iron. Steel seems the most common for piers, however others have suggested just going with Aluminum as it is apparently much cheaper and easier to work with. On top of that. It doesn't rust like steel.

Now.. if I tossed together a 6" or 8" diameter aluminum pier, how thick should the metal be?
Thicker than a steel pier? Does it matter?

I'm open for all sorts of suggestions. Cost is a factor for me Gotta keep the wife happy, and the baby fed!

Gary

The following website has a listing of sites under the topic "piers" which may be helpful, as well as a link to "the basics of pier design".

I'm sending you a private message.

Marc-Andre