Shipping question

Hello, I see some problems with the displayed shipping prices.

First, I offer 3 shipping categories: free (with purchase 20 or more), .70, and 2.50.  My listings show 2.50 as the "starting price" for shipping.  However someone may want to buy a card and choose the .70 option, but go with a different seller because they think that 2.50 is my cheapest option.

Also when checking other sellers shipping costs, I might see .50 as the listed lowest price.  However when I go to checkout, the cheapest option is something else, like maybe .65, and there is no option for .50.  Am I missing something?  Sorry for the ignorance but I am new here.

I think the easiest way to handle this is to have an icon like the "i" for my own listings, and when a customer hovers over it, all of the available shipping options are shown in a little pop up.

So does anyone know how I can make my "starting from" .70 in stead of 2.50?

Thanks!