Milling does have valuations similar to disenchanting and prospecting. I have the code written for enchantrix, and it is being tested (as quickly as I can gather or buy herbs on every faction of every test server). But it will take a while to gather accurate tables of yields. Unfortunately, the big database websites are not gathering useful data at this time. Also, Blizzard keeps changing the milling yields with each build. I swear someone there is toying with me. :-)
Btmscanner and the search UI will need additional modules written for milling - after I get the enchantrix parts working. Fortunately those will be almost direct copies of the DE or prospecting modules.