I can usually supply strings and fret gut by return of post. Please email me your requirements or give details of your instrument and I will be happy to suggest suitable strings and prices.
UNDER CONSTRUCTION:
Different string materials need different diameters for the same string tension and for overspun strings different manufacturers use different systems of guage numbers. For easy conversion from one type of string to another, see the String Conversion Table.
For calculating string tensions for a particular instrument see ???'s website.
For a summary of the properties of different types of string, see Lute strings ancient and modern.
For further reading see Strings: Bibliography.