Is it the cvast iron manifold or the down pipe thats gone, or is it just a gasket?
The manifolds seem to fail, mine has cracked and I've seen a few in scrap yards with the same problem, inc some that had been welded up. If you can weld that might be worth a trip, take it for a good thrashing to get the cast iron hot, quickly in with an angle grinder to reveal some clean metal then in with the welded or full chat to weld it up. If it doesn't work you've not lost anything.
If its the down pipe(s) they're available think mine was about £80 but not sure might hgave been more. The problem is getting the Lambda sensor out, mine stripped its threads so I had to buy a new one of them too.
If its gasket at the head, I've no experience, but theres no gasket from the manifold to the down pipe(s) just 2 stainless steel sealing rings, so it might be worth just tightening the nuts up hard to see it that cures it.