Quick INS question

[xalaii]

how much does it cost to make 1-450 inscription with buying herbs from AH?

[Yerbury]

How long is a piece of string?

Seriously, the answer to your question depends upon the supply and demand of your server.

Best thing to do is have a look on Wowhead (or a similar site) in the forums section, and review the profession guides. There are one or two Inscription guides that will give you a clue as to the best types of herbs and the amounts required, so that you can level as efficiently as possible.

[AngelExodus]

I wondered why I passed a scattering of illegal immigrants running away from this thread...

But to answer the op, yes it depends on the economic status of your server, the flavor of the ah for the day, and if anyone else decides to lvl inscription at the same time as you and you have to fight over the mid lvl herbs or pay extortion fees. The best (and most obvious) tip I can give you is to get a list of all the pigment categories and search for all the herbs to find the cheapest ones for each category.