Payment workflow with variable price

[brianwerts]

Can Shopify or an addon support the ability to take an initial payment (10% of estimated price) then when the product is ready to be shipped take final payment where the price is based off of weight. 

Use case #1

I'm selling a product by weight and I don't know final weight till it ships, but I need to take a deposit to ensure customer doesn't back out.  So the customer is PreOrdering the product based on estimated weight and set price/lb. 

Example:

- Customer logs in and selects product that cost $2/lbs and estimated weight of 100lbs for a Total Estimated cost of $200.  

- Customer does a partial payment of 10% ($20) with the estimated remaining balance of $180.

- I then make the product and ready to ship it weighs 120lbs for a total cost of $240 (minus the Prepayment of $20).

- The customer now owes $220 so the Invoice needs to be updated and the final invoice sent out and paid through the platform.

Use Case #2 - Same workflow as #1 just based on hours not weight.

Is a software development company where I contract for an hourly rate of say $20/hr with an estimate of 10hrs for a total of $200.  The customer then pays 10% up front but when the work takes 20hours a final invoice has to be sent for $400 minus the 10% upfront fee paid.

Is there a solution with Shopify to complete the payment workflow?

[sg13]

Also looking for solution in a very similar scenario, for a service that takes a deposit, gives an estimate in $ or Hrs. then charge the final price minus the deposit, any help would be much appreciated.

[mimiT]

did you ever find a solution for this? I need help with this as well.