There was a program on Create TV which showed a very cheap and effective system.

Here's the link. The entire episode is pretty good, but the fencing info is about halfway through... http://www.growingagreenerworld.com/building-a-garden/

Thinking about this T post.

My deer fence is those posts (5' above ground) with two rolls of 3' galvanized wire making a 6 foot high fence sticking 1' above the top of the posts. The deer do not jump it, though they certainly could if they were really motived (i.e. in the winter). The groundhogs also do not climb it either but I had issues with digging and had to make the base more robust with chicken wire to prevent digging.

I'm not sure this is a cheap solution, however. chicken wire is much cheaper, plastic deer netting much cheaper still, with cheaper plastic stakes.

I'm thinking of just running just metal wires, not the mesh. Deer would not squeeze 1' to 2' gap to get in. They have been exposed for this whole season and the damage is still very limited. I have the animal traps open for the small ones. But there is no way to eliminate rabbit and groundhog problems.

Yes there is. They can not dig under my fence, I have the base lined with chicken wire bent outwards and buried under mulch. Of course, no fence is foolproof.

Yes the chicken wire will fend off the small animals. But it is way off my price range. I do not even want to spend more to expand my 7' deer fence. I do not know when I can get back my investment in deer fence. The smaller area is 90' x 100'. So cost is clearly the main consideration. At this point, I only want to install a very basic deer fence and discourage the deer, but not completely deer proof.

I'd price compare then and buy the least expensive as you want... deer are lazy in the summer.

The other thing I'm thinking is to use the existing trees as posts. Then I run three or four strands of metal wires and fence off the area I want. Then the area will be like 50'x100'. With the wires placed 1 1/2' between and 6' high, there is little incentive for the deer to jump inside. Of course, they can still dump in, or sneak in....