I built this probably 15-16 years ago to start seeds in tray. It later evolved into a display unit in my on farm store. While remodeling the store and upgrading it to a commercial kitchen the old shelving unit found its way to the corner of a barn and was forgotten the last couple of years. Until I was cleaning some junk out of the barn yesterday and found it sitting there in the corner, begging to be put back into service. It is a small unit that only holds 12 flats of seed cells but that is quite a few plant starts for a hobbyist or homestead operation. I have not dressed it up to its full former glory in the pic. I have a clear poly sheet that latches on to the front and need to staple plastic to the back of it. The lights are phillips full spectrum bulbs and are $39 for 10 in a contractor case. The ballast are $11.99 cheap shop lights from home depot. Shelf unit was made from scrap wood, poly sheet was a deformed one from a greenhouse, and my total cost for the unit came in at around $100. Enough head room to go from germination to good size plants. And my light raising and lowering system is just a hole drilled in the shelf boards and the light chain fed up through the hole with a nail or length of wire through the chain to hold it in place. Making it very easy to raise and lower the lights, without fooling around with hooks in a tight space. It beats the heck out of those junky stand up greenhouse kits and cost about $1500 less than a comparable pro germination chamber.
I wish I had the space to use those 4" pots for starting I start in 72, or 128 cell trays and transplant to the 4" pots for the plants I sell at our Farmers' Markets. Had to drag all of the potted plants I could inside anywhere I could fit them as we had 3 overnight below 20 degrees and my high tunnel won't stay warm enough to protect the cold sensitive plants like the tomatoes, peppers, and egg plants and I am not going to artificially heat 48,384 cubic square feet of high tunnel LOL. And the greenhouse was packed to the gills so I took over the starting rooms, my workshop, the spare bedroom, the kitchen and the living room and trust me the wife is not happy with me right now Sometimes the simplest solutions are the best. I look at these plant starting systems ranging from Hobbyist level to Pro Grower and in all I am just not seeing where you get much bang for your buck.... Unless you want to just say "Hey I spent $27,000 on a germination chamber!........ Errr that I could have built and probably longer lasting and better for $2,000."