Join Date: Jan 2011
Location: West Chester, PA
Most 4x4 posts that you are going to find are pressure treated Southern Yellow Pine and also rated #2. The #2 rating refers to the quality of the wood. It is fine for fence posts and deck supports, but not really intended for finish work.
There is architectural wood $$$$, #1 $$, and #2 $. If you are planning on staining and finishing this stand to a furniture quality stand I would probably steer clear of pressure treated #2. Although structurally sound, it will have a lot of knots, irregularities, a green tint from the pressure treating process (used to be copper chromium arsenic, but changed to another copper based chemical can't remember exactly what it is), with a more likelihood of warping. Additionally, the wood will often still be wet from the pressure treating process and will take a long time to dry out (several months). This moisture from the pressure treating process can also cause problems if you try to stain the stand before it is completely dry. The moisture will be trapped deep inside the wood and may cause your finish to fail.
If you are set on 4x4 construction, Western Red Cedar may be a viable option that is fairly common and not crazy expensive. It has a nice straight grain and mills nicely.