For instance, consider the the alcohol stove used in lightweight backpacking. The more one searches for information the more you learn about the advantages and, of course, the disadvantages. I will not present the arguments here but there are some links that have good explanations: http://www.interfree.it/index.html also
You will discover that alcohol stoves are a good Do It Yourself project, in some cases it has become a cottage industry. The design and building has become an addiction for some. If you do not want to build your own stove there are plenty of designs available that are reasonbly priced.
What is fascinating about bike touring/backpacking is that it does not have to cost a lot of money. I'm not saying that you should or could make your own shoes/boots but there are many items of gear that are good candidates for the DIYer. Do some searches, you may be pleasantly surprised.