It's all dependant on the prices on your realm.
Personally I prospect all the ore I can get my hands on;
I assume it costs me 12x the cost of 1 stack of GIO to make 1.2 (transmute master) meta-gems - currently GIO sells for 60g~ a stack on my realm which gives me an average crafting cost of 600g per meta-gem - currently the good cuts of meta-gems sell for 1100g~ so I'm making profit just on the meta gems - I then cut my reds/yellow/blue into any that are profitable (>100g - which isn't many) - I then use the remaining rare primary colours to craft i450 jewelry which sells pretty well on my realm and gets rid of all the serpent's eyes I've stacked up. As for the common gems they get crafted into rings/necks where I disenchant the greens and ah the blues which are also still selling really well which I guess is people starting to level alts.
As for your questions directly - 20-30g for a stack of GIO is insane - I'd buy it all out right now! I don't have blacksmithing but I understand you can make profit atm making the i450 armor.
Also I mill all my herbs mainly to keep my glyph stocks afloat - I do intend to get into the potion/flask market later in the expansion though.
I'm transmute master (helps when creating the metas), I'll probably level another elixir master alchemist later in the expansion.
Hope that helps.
Last edited by rkrowland; November 7th, 2012 at 06:40 AM.