Quantity + Screen Printing = Price?

Hey guys, this problem is driving me crazy.

I need a way (ASAP) to give customers a way to specify that they want a certain article of clothing to be screen-printed.

It needs to work like this:

Customer needs to purchase a minimum of 24 of a certain article of clothing to qualify for screen printing.

So on each clothing product I need the following:

NOTE: A minimum of 24 of this product must be purchased in order for us to screen print your garments!

Quantity to be screen printed: [text box] (This will add $3.00 / unit to the garment's price)

Thanks in advance for anyone's response, I would GREATLY appreciate it!

When entering this product jujst add the base single unit price in the price block.
further down there is
Product Qty Minimum:
Product Qty Maximum:
Product Qty Units:

In minimum enter 24
maximum leave as is or as "0"
units stays at "1" unless you want to force blocks of say first 24 then in blocks of 6

For the rest see
https://www.zen-cart.com/tutorials/index.php?article=57