Picked up one of these, which is 20" wider than the one I set up.
Gardman Indoor/Outdoor Extra Wide 4-Tier Greenhouse with Reinforced Cover at Blain's Farm & Fleet
I think for the price these are really a good value. They do require some mods though, as I outlined earlier. Here are the mods from stock:
added 5 inches to the lower shelf height. (now 17")
added 8 inches to the main growing shelf. (now32")
2 circulation fans in the lower level and 2 fans in the upper part of the tent. run 24/7
1 ventilation fan that pulls outside (room) air INTO the tent for 30 minutes, twice per day.
Many cable ties to hold the shelves flat. (They feel MUCH sturdier if you do this)
3/16 hard plastic on the bottom.
I actually had to steal some parts from the small greenhouse to extend both shelf heights. Also had to cut the leftover tubes.
The nice thing is that running 6 of Ray's LED lights in the smaller tent, only raises the temp by about 6-8 degrees. No continual venting keeps the humidity much higher than the room humidity.
Should hold 8-10 orchids, with the low light ones on the bottom. Also have a seeding heat mat on the bottom for s/h transplants.