I've revised the price list a touch, throwing in some guesses for miscellaneous parts and bumping shipping (which informally includes any parts I've forgotten to include) up to 400$.
A general rule is that projects tend to cost significantly more than planned. Normally I go half again when making estimates but this is the first time I've done such a detailed list.
A final change I made was a fairly significant modification to the cover. I will be using 8 blind joints and 6 meters of their panel clamp rubber strip to embed 3mm acrylic in the cover. The change is about 20$ (Without the acrylic). I will also try to combine a green laser in with the CO2. I estimate that change to cost 50-80$ depending on what I can get the window for.
I am also strongly considering upgrading the Z table. The current material is 20 gauge aluminum sheet with hexagonal perforations. For 35$ more I can buy a 48x24" sheet of 1/4" aluminum honeycomb. Another 20$ upgrades that to 3/8" thick. Mostly a cosmetic upgrade but it will stay flatter and have less back reflection. I do plan on building a box under the Z-table for air intake and having something to put on top of the honeycomb because I intend to do a lot of paper cutting. I looked into thin steel sheet with 1/16" perforations but all of that stuff is really expensive so I'll probably end up drilling holes in some scrap.
I will be putting enough time and money into this project for a few cosmetic changes to be worthwhile (this is how my projects get expensive :/)
It appears that the retina and keling stepper drivers will play nice as long as I don't run any 5v inputs back into the retina. Shouldn't be a problem. I will probably cut the wires off a 12V wall-wart and drop some of it to 5V and 3.3V for the miscellaneous electrical requirements. I also have a few computer power supplies kicking around but they are all fairly large so I'll see what there is room for.