I fixed the problem with a really simple solution. I changed the following line in the add to cart button:
$ATC_itemPotted = "".$_POST["eCart1_2_Potted_Add"] ."";// column binding
This adds the price increment based on the select list.
Also, I changed the <option value="<?php echo($rsPotted->getColumnVal("ProductOptionID")); ?>">
to: <option value="<?php echo($rsPotted->getColumnVal("OptionPriceIncrement")); ?>">
This solved the problem that was driving me crazy or hours.