What the Per Unit perweightunit module does is let you enter what you want to charge for shipping per Product per quantity ...
So if you enter on the Product Weight .50, it would charge $0.50 ... if 2 were ordered then it would be 2 x .50 or $1.00 ...
The one draw back is, when you switch to USPS you will need to re-enter all of your weights for your products ...
As to what to do with USPS, to get correct Rate Quotes, you would need to enter the information for where you are shipping from on the Configuration ... Shipping/Packaging ... this way the rates will match where you are actually doing your shipping from ...
To customize the Per Unit perweightuni shipping module for making it a minimum of $3.50 you can edit the file:
/includes/modules/shipping/perweightunit.php
and change the code for:
Code:
$this->quotes = array('id' => $this->code,
'module' => MODULE_SHIPPING_PERWEIGHTUNIT_TEXT_TITLE,
'methods' => array(array('id' => $this->code,
'title' => MODULE_SHIPPING_PERWEIGHTUNIT_TEXT_WAY,
'cost' => MODULE_SHIPPING_PERWEIGHTUNIT_COST * ($total_weight_units * $shipping_num_boxes) +
(MODULE_SHIPPING_PERWEIGHTUNIT_HANDLING_METHOD == 'Box' ? MODULE_SHIPPING_PERWEIGHTUNIT_HANDLING * $shipping_num_boxes : MODULE_SHIPPING_PERWEIGHTUNIT_HANDLING) ) ));
To read:
Code:
$this->quotes = array('id' => $this->code,
'module' => MODULE_SHIPPING_PERWEIGHTUNIT_TEXT_TITLE,
'methods' => array(array('id' => $this->code,
'title' => MODULE_SHIPPING_PERWEIGHTUNIT_TEXT_WAY,
'cost' => (MODULE_SHIPPING_PERWEIGHTUNIT_COST * ($total_weight_units * $shipping_num_boxes) < 3.50 ? 3.50 : MODULE_SHIPPING_PERWEIGHTUNIT_COST * ($total_weight_units * $shipping_num_boxes)) +
(MODULE_SHIPPING_PERWEIGHTUNIT_HANDLING_METHOD == 'Box' ? MODULE_SHIPPING_PERWEIGHTUNIT_HANDLING * $shipping_num_boxes : MODULE_SHIPPING_PERWEIGHTUNIT_HANDLING) ) ));