Ability to charge additional fees if the customer chooses to not pay in full

Ah, so for example if the product normally costs $100, but the customer chooses to pay by down payment, then you might up the price to $110 total?

I like it!

I fixed this with a custom module to grab the downpayment
justt make a custom module and use this to adjust price...

here is the code i used:

uc_downpayments_add.module

function uc_downpayments_add_cart_item($op, &$item) {
    switch ($op) {
    case 'load':
$item_info = node_load($item->data['node_checkout_nid']);
 $product = node_load($item_info->field_productid[0]['value']);
$item->price = $product->downpayment->amount;
 }
}

uc_downpayments_add.info

name = UC Downpayments ADD 
description = add to nodecheckout nodes.
core = 6.x
package = Ubercart - contrib


; Information added by drupal.org packaging script on 2011-10-25
version = "6.x-1.x-dev"
core = "6.x"
project = "uc_downpayments_add"
datestamp = "1319502905"

Nifty!