we're looking to do a 4 week road trip starting in Split and <!--{C}%3C!%2D%2Dtd%20%7Bborder%3A%201px%20solid%20%23 cccccc%3B%7Dbr%20%7Bmso-data-placement%3Asame-cell%3B%7D%2D%2D%3E-->Tirana, we'll be zig-zagging between countries.
I was hoping you could tell me which car rental companies have an one-off cost for border crossings and don't charge you for every time you cross a border.

Thank you

Assuming you are from the US, I suggest calling autoeurope.com or kemwel.com and see what they can offer. We have used both companies and have found sometimes their policies differ with regard to taking cars to different countries.

We're based in Australia

even based in Australia I'd use the first one first, but you may have to email your requirements