Sounds like a plan!

I just use this (I've found it on the net for $39)...

http://www.amazon.com/4-shelf-Greenhouse/dp/B0009J3EX2/sr=8-1/qid=1154446134/ref=pd_bbs_1/102-9215549-3856960?ie=UTF8

Here is a link that might be useful: Greenhosue on Amazon

thanks for the link.it not exactly what i need but thanks.some of my guys will get fairly big so i need fair space between the shelves.minne have about 3 feet of space. i would like to mount some quadruple fluorescent fixtures insde it on two levels.will it be ok for my carnies?i will be looking for polyurethane (major typo i think) tarp to wrap it in.another option is using some cheap tarp around and using a plexiglass door on the front with hinges.im wondering how to keep the humidity up since it wont be airtight.i will need some air from the outside since i will be growing orchids which need decent air current.i could mist often with aquafina so no calcium deposits.i will place some trays of water inside to help.do you guy have any good suggestion to help things along?

First off...the shelves are removable. Each level is split in half so you can remove one shelf or the entire level. I grow my Neps in almost the exact same thing. There are two approachs to humidity that I use.

1) I have a large plastic tub in the bottom of the chamber which is filled with water. 3 airstones are connected to a aquarium air pump which resides outside the terrarim. I'll cost you about $12 for the pump, tubing, airstones, and plastic tub at Walmart. Downside is that humidities above 70% are difficult to attain or maintain with this set up.

2) In my highland nep chamber I use a 2 Gallon Ultrasonic Humidifier from Walmart (about $25). This can pump humidities up to over 90% with no problem. I have it on a timer which is set for 1 hour on, 2 hours off. Humidity cycles between about 68% and 90%+. Ideally, I would prefer to run it 20 minutes on and 40 minutes off; but I haven't found timers that really support those short inteverals easily.

I have fans operating inside of all my terrariums, even my 20 gallon long tanks. If you poke around, you can see some of my setups on this forum.

The shelf wardian house idea should work. To my mind there's a few potential problems that you may need to tackle before they arise.
-Is the wood treated? If not, will the increased humidity cause any problems with rot?
-You're mounting fluoro's in 2 of the 4 shelves. I don't know how deep the shelves are but, assuming the remaining 2 shelves will only receive natural light, the leaves and flowers may bend towards the light. It's really only an aesthetics problem so you may not care.
-You want to add fluorescent lights. The ballasts will put out a lot of heat. Any plants sitting on the shelf above the fixture may not appreciate it. You can get remote ballast fixtures although these are expensive. You can save money by rigging up a standard fixture to isolate the ballast away from the shelving. Unless you know an electrician, I'm not going to recommend this as it's potentially dangerous. Another thing to remember is that standard shop fixtures aren't water resistant and components rust easily in humid environments. You may need to replace them every few years.

Your shelves should work well.

I have used the cheap plastic shelves in much the same way. I would just skip a shelf and put the legs directly together. For extra width or length I duct tape a pair either end to end or front to back. I then tape mylar to the back and sides while using clear plastic on the front for the door.

For humidity I have a tray with egg crate over it in the bottom. I keep an inch or so of water in the tray and have a small computer fan on the egg crate, blowing the air down towards the water. I have no problem keeping humidity up to 90% or as much as I need.

I have used regular shop lites in these units as well as floresent work lights. Now I think I will try some of the cfl's if I make another one.

John