large panniers/beginning touring
If you really are just checking it out. I'd suggest getting a very inexpensive set of panniers that you might find on Craigslist for your first tour. They may continue to be useful to you when you want a friend to try touring later, and s/he may want to use them to test the waters. They can also be good for short 48-72 hour tours where you can manage whether you are cycling in rain, etc.
Once you know you like it, use your Amazon card to get, or supplement getting a very good piece of equipment.
If you intend to do epic touring, you will want waterproof panniers. Using cheap, used equipment will help you know what you like and don't like about specific types of equipment before you spend what resources you have.
I began with a used set of Transit rollers that I got 4/$60.00 from a friend. I used them until I was about 1000 miles into a big tour, and just fell into a great deal on a pair of Ortleib rollers. Bought the Ortliebs and now use the Transits for friends as they consider touring. I'm big on loaning things to folks to peak their interest in cycling.
Cherri