Is it possible to limit payment / checkout options over a certain amount?
For example limit payment/checkout options over €1000 to manual / invoice and/or another 3rd party payment (eg humm/klarna). (Payments under the amount would have all regular checkout options available shopify Payments/PayPal etc.)
To protect against online fraud / charge backs etc for larger amounts…
b) If you want to get notified on those orders, you can use Order Automator app. This can identify orders over X amount, can even cancel the order if it’s over X and used a certain payment method (if you do this I would combine it with idea A to give clear expectations to the user.
You can also use this app to identify high risk orders (either notify staff or auto cancel). That feature comes included in the free version.
c) You can edit your order notification email, using Liquid / variables (Reference: https://help.shopify.com/en/manual/orders/notifications/email-variables) so that if order total is over X then show a message that this order requires a different payment gateway, reply to this email to complete your order… something like that.
To protect against fraud customers and limit payment options over a certain amount, you can utilize PayRules: Hide Payment Methods app. So according to your example above, let’s hide Shopify Payments and PayPal if the order amount is over €1000.
Select Shopify Payments and PayPal from the Select payment methods field.
Write 1000 in the Cart total Max (maximum) field like the screenshot below.