But the car mechanic will say "I see where you're coming from but I have this age old arrangement where I service and polish these lovely Mercs and Audis. Thanks but no thanks."
Also, you seem to forget its only the English which always like a bargain. Money is only part of the consideration in other countries. Cheapest is not always best and the reason most German taxi drivers drive a Merc.
German Mercs are mostly diesel and a lot cheaper than the Mercs we buy here, especially as we pay import tax on them, and they don't. And it isn't only the English who like a bargain. They think you're nuts, in foreign markets, if you don't barter with them. They snigger to themselves if you just pay whatever they ask.
We are doing increased business with China and Brazil, the two greatest growing economies. We've always kept on the good side of India, even sending them aid while they are richer than us. We have long had a "special relationship" with the USA and we have our Commonwealth partners. Who says we will be friendless and out in the cold if we leave Europe? If we leave Europe, then watch France, Germany, Italy and Spain wish they could follow us, but they don't have the contacts outside Europe that we do. They all need us far more than we need them, but the powers that be, would like to try to convince you otherwise.