Well... personally I wouldn't use latex on minis. I'd be interested to see some photos of it used on tanks, and to know how durable it was?
I would avoid home depot all together for miniature painting. All of their paints will have a whole lot of extra junk in them as they are not meant for small detail painting.
I had a similar plan for my cityfight terrain... I wanted uniformity (and cheap).
This is what I would do: put some of your final mix, and each of the components on some white paper to use as reference. Head over to your local arts&crafts store (michaels,
ac moore etc) and find the cheap Apple Barrel acrylic equivalents. They will likely also have Liquitex (not as cheap) acrylics, inks, airbrush medium, etc. Both will get you large quantities for cheaper than
GW prices.
Buy some small plastic (empty) paint-pot-cups and a few _large_ empty paint dropper bottles (make sure they have caps that will seal).
At your local pharmacy buy some distilled water and some cheap Isopropyl alcohol (91-99%).
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Mix your paint/inks to get desired color. Once you get the right ratio extrapolate that to the large paint dropper bottle and add a little distilled water. Shake and your paint mix is ready to go.
In the second large dropper bottle add a mix of 7:1 distilled water: Isopropyl Alcohol. (this is for the airbrush)
Paint as normal with the first large dropper. When you are ready to Airbrush, in your plastic paint-pot-cups add some paint and then some of the Alcohol mix, shake/mix and try to achieve a 'milk-like' consistency (or skim if using a really small needle) then pour into airbrush cup - spray away.
Use the same alcohol mix to clean
AB between colors, though I would recommend using a legit
AB cleaner once you are finished.
This is what I would do / have done anyway.