Scorpiono on "Advanced: Query a custom_post_type and assign it a category"

Hello folks,

I have quite an issue.
I'm using a custom post type called "Tee" to store a t-shirt gallery.
Every t-shirt is a post within this CPT with a custom meta field called "Price" (http://d.pr/i/GRQy)
Every "Tee" has a category called "Prices" as well (http://d.pr/i/1mi9)

How can I query the database to assign every post, the category $10-20 (Prices) if the custom_meta_field is $13 for instance?

I have a rather large database and going manually is quite a task.
Deeply appreciate support from a hardcore hacker.

Thank you,
-Sergiu