Bikeshops and Belgium ...

The best bike shop as far as cost is Van Eyk in Aalst, Belgium. Their prices are very good and they have a sale in July and December. You can also look to mail order places in Europe including Chain Reaction and Total Cycling. Your local bike shop can be a good and cheap source for parts. Just a quick introduction to the owner and some short conversation can lead to some cheaper costs on things (especially tires and tubes).

Links:

Van Eyk - http://www.vaneycksports.com/

Chanin Reaction - http://www.chainreactioncycles.com/

Total Cycling - http://www.totalcycling.com/

Bike 2 Build - http://www.bike2build.nl/