Obviously price is a consideration, but if you can make those exhaust clamps cheaper than the Burton clamps, I'd be interested.

Ah, so you're talking about the exhaust clamp. Now that's a lot simpler. I assume you need a set for all the joints? Be aware that I used low carbon steel with no coating so it would quickly develop some surface rust. But I only made one, as the standard clamps do fine on other exhaust joints in my car. The raw cost of this one (with the clamp) was 20 PLN, which is around ~3,50 GBP at the moment. The securing clamp of course has a fixed price of 5 PLN (~1 GBP) but other elements might be a bit cheaper even in such a small series. With one piece you always have to pay someone just to take to the work I'd require a small fee, for my part of work and the time it takes to organise this. Then there's shipping cost (not much, but still). We could probably estimate around 30 GBP for the set (maybe with postage as well), but I can't guarantee. Don't you have someone with a lathe? Is this kind of work so expensive in the UK?
For other exhaust joints you'd have to change the internal diameters by 2 mm because they're larger, but that's about it.

I'm sure I could find somebody with a lathe who could do it, but I'd sooner buy a set from you, if you were making a few. I'd want a set of four to do the manifold/heat exchanger joints, and maybe the one for the swan neck too. I would not worry about surface rust, I cover all the mating faces of exhaust joints on copper grease, which usually goes everywhere anyway...

Saurus i am interesting about the crossbox leaking solution as untill know i ve repaired that spot 4 times with 2 different solution . I finaly welded a pipe in the pipe. The problem is still there so i would like to ask if it did solved ur problem.?
Sometimes the reason for a gas leak is a bend ( small like 5mm or something )end lips on the crosbox side.

It's been a few days now without any leaks. By this time they would've usually appeared. Also it fit wery well and made a very secure joint, so try this for a solution.