My be useful to know, to accommodate 1.2.1 the server PHP version is 5.6.  I need to switch to PHP8 which requires Abantecart 1.3.4

I found a solution! 

I found the module for weight based shipping had some flexibility. So I set all products to 1 pound and then in the rates entered 1:8.00,2:9.00,3:10.00 and so on. Since each item was listed as 1 pound it treated them as number of items instead of weight.  Then I had to go into the languages and change "Weight Based Shipping" to "USPS Priority Mail" to match what we wanted the option to be.

I also found that the default free shipping extension would indeed show up as a choice. So I set this at a minimum of .01 to make it always a choice.

As a suggestion, maybe add a parameter to per item shipping module to allow first item one price and additional items a second price. Other "carts" have the ability to do this and it seems it would be an easy add.

Also, it would be nice to have the ability in the extension to set the title of what that extension shows up as.

I need to be able to offer two shipping choices.
1. Free First Class with USPS
2. Priority Mail (USPS) at $8 for the first item and $1 for each additional item.

I'm having trouble finding a configuration of extensions that will accomplish this. First, the per-item module doesn't offer a second price for additional items. Second, it seems if I add Free Shipping as an option, then it overrides the other options price and lists all options as free.

Any ideas on how to configure to get the desired result?

THANK YOU! I looked on the remote server and currency.php was not where you said. Maybe something went wrong with install. I uploaded the page and it worked perfectly. Much appreciated!