in reply to
Is Programming Perl still relevant as a reference book?
Is it relavant? Hell yeh! And beautifully written. I tend not to like learning from online docs (I find them more useful as a reference when I'm looking for a specific answer), so I read lots of techie books. I've found the camel amongst the best - it's pretty comprehensive. Its very densely written and would not be an ideal beginners book, but it sounds like you're looking for something fairly in depth.
On the cost issue, I don't know how the public library system works in Finland, but here in the UK you can ask your local library to acquire specific books for you - maybe that'd be an option.