Building up a set of tools is expensive, but a good investment. The bike itself will be as cheap/dear as you want to make it. Read this a few times, then worry about saddles and handlebars: Obligatory Sheldon brown link
@Velocipede started
London Fixed Gear and Single-Speed is a community of predominantly fixed gear and single-speed cyclists in and around London, UK.
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Building up a set of tools is expensive, but a good investment. The bike itself will be as cheap/dear as you want to make it. Read this a few times, then worry about saddles and handlebars:
Obligatory Sheldon brown link