I don't know... I think cattle panels are a good place to start for SternRose. Cattle panels are pretty darn cheap and extremely easy to put up. If you built a 16x16' pen out of cattle panels, your costs would be: (this doesn't include a gate, but you can rig one of the panels to swing to allow you and the mini to leave and enter)
4 cattle panels @ $20 each = $80
8 T-posts for (corners & line) @ $4 each = $8
Total = $88
You can zip tie or use twine to tie the panels to the T-posts.
Field fence with wood corner posts and T-posts for line posts IS awesome, but you have to buy THE WHOLE ROLL which is expensive. Field fence would not work well for a 16x16' enclosure. Field fence also looks and performs like crap if it isn't installed properly. It needs to be tightened - REALLY tightened - and requires corners with bracing to prevent it from sagging. Good corners usually require at least 3 8" round posts sunk in concrete, and then braced horizontally and diagonally. It's a whole lot of work, but it looks great and lasts way longer than any other fence if done right.
Wood fence looks pretty, but definitely does not last. Plus, sinking that many wood posts in KS clay soil can be a major PITA and expensive if you do not do it yourself.