With added shipping, tax, duty, etc one could get parts from a dedicated repair service facility or authorized full service third-party Apple reseller in the US or Canada, who stocks parts and specializes in repairs of portable Apple computers, would be a likely source for near obsolete parts and the services required to make these aging giants stand on their feet again.
Or send the computer to a repair facility that can do the work, out of country...
with proof you owned it for sake of return customs clearance w/o duty, etc.
Some of those who repair many products and have inventory of parts for many model build years, may be a place to ask. But their main business may not be in Parts, but a larger area of dedicated specialist repairs and restoring function to a variety of Apple portables, and maybe others. Shipping long distances is common place for the better ones, as they are known world wide thanks to the internet. I read up on wegenermedia.com in south carolina before I sent a portable Apple computer to them from Alaska for repair.
That one, I have had good experience in a service repair by mail across the continent, on an iBook some years ago; and I know this company has most parts. But they are in the repair business. One could ask if they do sell parts to non-trade persons; though there may be a problem in this if you can't correctly identify the computer and then get the wrong parts. That can sour both sides of the exchange. I'd see if someone can acttually repair the computer at a reasonable price; even if you have to sent it in a padded box. There may be a company in the UK, for example.
Other companies that used to do repair no longer exist or do not work on older gear; so I have bookmarks from up to ten years ago and have found even after searching the web, there are fewer who fix old stuff. So that may be the route, to either get a working older one with guarantee or get yours fixed up well enough to keep and use. Until the next time something goes out.
I wasn't going to write much, but the time here is like 2AM and I'm doing a zombie like stare at the Mini G4 screen (some korean LCD) and it's past sleep time for me...
Hopefully you can get it going...
Good luck & happy computing! 🙂