What I had realized, is on my server.. tin was very cheap, and the gems you got from prospecting were EXTREMELY EXPENSIVE. I bought about 20 stacks of tin ore for like 35g, and later sold all of the gems I got for about 226g. (30 moss agate, 32 shadowgem, 41 lesser moonstones, 6 aquamarine, 1 citrine.)
To speed the prospecting process up, I grabbed a book, made this macro, then put it on my spell bar, and spammed for 10 minutes while I read a book.
/cast prospecting
/use Tin Ore
Not everyone's server is going to have the same situation as mine did. Try searching other low-mid level ores, then check out the going prices of the gems, and add it up. Mithril( = aquamarine, citrine, star ruby), Copper( = tigerseye, malachite, shadowgem), Thorium( = star ruby, large opal, blue sapphire, azerothian diamond, huge emerald).
I sold them all in singles, by the way.
-Blugahin.