In the attribute module I replaced

line 450 $item->price += $op_prices;

with

if($op_prices == 0){
$item->price += 0;
}
$item->price += ($item->price * $op_prices);

I used Restrict Qty to limit selection to just the attributes for the product, and created attributes including a 'price' as a multiplier. This was for a fabric retailer, so I had two sets of attributes. One for 1/4 yard = .25, 1/2 yard = .5, etc. And one for 1 = 1, 2 = 2, etc. I'm sure that using this with weights could be the same. I hope that something like this is implemented soon in core.