I would never circumvent any rules to accomodate a seller. If you sell on eBay, you do everything through eBay and use Paypal; if you use Paypal, you pay fees.

If there's a dispute, everything needs to be documented and correct.

If the seller doesn't like it, that's fine, they will probably be OK with relisting their item and trying to try it on with someone else. If it means you don't get the product you want, that's fine.

I've sold many things on eBay, and have communicated with buyers in other countries and negotiated a price (lowering a "buy it now" so including a shipping amount arrives at the negotiated price, for example), but it always must be paid for and completed within the system - always always always.