Allow setting a custom price in the GetPaid shortcode

[picocodes]

No description provided.

[aayla-secura]

I think this feature request can be expanded to "allow adding the same item multiple times to the cart/invoice with different properties, e.g. different price". This would be a great feature to have. I'm currently building an addon for your plugin and I've laid out the codebase for this, but the main obstacle is that WPInv_Invoice add_item method removes items with duplicate IDs, and there's no obvious way around that. Is it essential to have this bit of code there? Can you not allow adding items with the same ID multiple times (which currently is of no good use without extra code, but as I said for someone like me developing an addon it's essential)?