I am doing just this. I am starting over again after not touring for 10 years and no longer have my old bicycles. I will be bugeting myself and would like to say a couple of things I will be doing and recomend to others.
1. You can only shed X amount of weight off your bike and it costs alot to get these ultralight bike parts. If you try to cut the weight off your camping gear you will save more weight along with more money.
2. You don't need a top of the line frame. I will be using an old chrome molly mtn bike. It will searve my needs as its strong and durable.
3. CONSIDER YOUR GEARING NEEDS. I don't use the lowest gears on bikes very offten and I always wish I had a higher gear. In my case I will deffently wount to get a 11 gear for my smallest casset.
4. Keep that bike well tuned and cleaned. A well kept bike is an easy bike to ride. I have taken the cheapest bike from wall mart and tuned it up top to bottem and found it had a very very good ride. At the same time I have seen Trek's that road ruff becouse of lack of mantance.
5. CHECK THAT FRAME. I have had a frame brake and cause me to roll over the bars NOT FUN.
6. Take your time and examen your ride. Your touring not racing. There are things to see, smell, taste, hear, and just enjoy. If you don't have the time for doing this then take a shorter trip so that you can.
Just my two cents.