Thanks.
Now I just have to find my personal balance between how big I'd like my greenhouse to be and how big my budget will allow :) .
I read somewhere that the electrical conduit is better for another reason. If you're going to use plastic, instead of a tarp as you did, PVC reportedly causes the plastic to break down faster for some reason. Haven't tested that out for myself but it's just one more reason for me to go with the less expensive conduit.
When I do get my gh project under way, I'll be sure to post pics to share with everyone here.