Desperately need help on how to price my shipping

Hi all,
I am an extremely frustrated newbie to running a business on the web. I design my own greeting cards and am trying to get my website ready to open. The problem is with how to price my shipping.

I am using Cubecart and unfortunately their standard shipping modules don't allow me to use the pricing structure that other sites seem to use for their greeting card shipments. This is an example:

1 - 4 cards $ 1.50
5 - 9 cards $ 2.25
10 - 19 cards $ 5.75
20 - 49 cards $ 7.85
50 - 99 cards $12.00
Anything over 100 cards, they only show prices for FedEx (different speeds) or USPS Express Mail.

Since the free shipping mod that is supposed to be able to do this is not flexible enough, and I don't want to pay for a commercial mod, I am wondering if there is another way to skin this cat. Instead of the structure these other companies use, I am tempted to offer free shipping in the US and just increase my price to cover it, and then add a flat handling fee to cover my shipping materials, gas, etc. Where I am stuck on that idea is how much I would need to raise my price to be an appropriate amount--since the ratio of units:shipping price doesn't increase at a constant rate, I can't figure out how to do it.

If I did that, I am also thinking that I would need to instruct my customers to email me if they need an order over 100 cards, faster shipping than USPS 1st Class or International shipping. This would be a pain, but I can't figure out how to automate it in Cubecart if it isn't a constant per unit amount.

Is there someone out there, either with Cubecart experience who might know how to make it work, OR someone with better business math skills than I have who could tell me how to calculate a per card price increase that would make sense??? Please help!!

Thanks,

Fridaydreamer

 

Anyone?

Fridaydreamer