Help w/ Pillars?

Here's my situation...I carved a welcome sign from styrofoam and painted with a faux stone finish.

Hawks Hill Sign :: Hawks Hill sign - Painted picture by hawkshillhaunter - Photobucket

This was to stand up high on posts at the corner of my yard but because of the shape and stone finish I'm thinking it would make more sense to be lower to the ground.

Here's a similar idea of what I want to do: http://www.shorebreeze.com/photos/SH-Sign_small.jpg OR: http://www.thestonecenter.com/images/sign_sm.gif

but the sign would actually attach to the pillars at the sides and the pillars themselves would be much wider to look unified with the sign. The sign is about 3.5ft wide x 1.5ft tall - i'd like the pillars to be at least 4.5-5ft tall so the sign itself is up off the ground by about a foot and still have room for the pillars to come up higher than the sign. I want it to be a strong focal point in my yard.

Any suggestions on the cheap/lightweight/easy-to-store way of building the pillars? I need to be able to take it apart so the sign itself can be stored alone to protect it. help?