In reply to Tim Chappell:
Hi Tim, I am a car mechanic by trade and three years ago, I set up my own business fixing bikes.
Compared to the cars I worked on for 25 years, bikes have a lot asked of them. The components really get a work out, so are always going to need replacing. Chains, sprockets/chainrings, bearings,cables, brake blocks are the things I replace most (after inner tubes of course).
I think you should invest in a bicycle maintenance course, then buy a few tools and then you could repair your own bike. Internet shopping enables you to buy quality components at a good price, you can even upgrade stuff.
I have two bikes, one is my town/pub/shopping bike and was given it. I have run it for two years, after converting it to single speed (as already mentioned and def the way to go to save money), I have spent nothing on it (after conversion). Not even a puncture.
The other is a trek mtb, which goes out now and then, on the trails when I have spare time. Now this can be expensive to fix, even doing it myself.
I believe if you get the right bike and look after it, you can travel cheaply for years without spending a fortune