an add on plexiglas door is about $80.. Nice to have, but not necessary ..
you can go and purchase some rigid plastic egg holders for that unit.. I hardly ever use my metal trays anymore..
I think Culvers has the plastic trays.. many chickn supply atalog have them.. shop around for the best price.. make sure they are the rigid plastic ones.. there is also a softer style, which I have also.. but you need to have trays to put those into.. or else they sag..
the rigid ones have 2 posts on 2 opposite sides which enable you to stack them.. a handy feature when you are saving eggs to hatch..
I removed the two outside rows of pockets from a couple of mine so that I can even stack them in the inubator.. that increases the capacity to almost double of the normal 24 doz.
If I remember correctly it adds 18 dozen more.. much cheaper than buying a second bator..