Handling fee only on certain items

[Hound]

I sell pet food. If I ship frozen foods there needs to be an additional $25 charge for coolers and dry ice per 50 lb order in addition to normal freight. How would I
go about setting this up for certain items only. I have over 500 products and this would apply to only about 100 of them. www.wholesomehound.com/index.php

I am doing this manually for now and not shipping anything frozen through the website.

[Ajeh]

What shipping methods are you using on your current site?

Can this be done via added weight on the product(s)?

[Hound]

I am using UPS XML. I have USPS but only use it for APO/FPO orders. I don't think it can be done by adding weight as the $25 extra fee is a single charge for up to 50 lbs. If they only order 5,10, 15 etc, the same fee applies.

[Ajeh]

How about by attribute using the one time attributes?

These apply charges once per product vs per quantity ...

[Hound]

I don't think that would work. If they ordered 5, 8 lb packages of the same product it would only add one small upcharge. I need $25 added to all raw food orders up to 50 lbs. If they only order 10 lbs the $25 still applies.

Ajeh, I do appreciate your thoughts and time. Keep the ideas coming.

[Ajeh]

If I order 1 8lb package what is the extra handling?

If I order 5 8lb package of the same product what is the handling?

If I order 7 8lb package of the same product what is the handling?