I'll just throw this out there, then will step back and let the touring experts take over. Start saving your money while also keeping an eye open on your local classifieds and thrift shops and bike shops. I've got a few panniers of various manufacturers that I've found at thrift shops, but I'm also looking to up grade them if they don't work well locally since my touring plans are still a ways out. Also do searches on craigslist and other online sites for "panniers" and additional searches for "touring", and watch for package deal bikes where the owner just might be willing to sell the bag set separate from the bike, it doesn't hurt to at least ask.

Don't be in a hurry, and don't settle for "good enough". Enjoy the search and research, and have a good tour.