What sizes are you looking for? Standard fractional in coarse and fine should be available locally for a decent price.
For metric and other than standard sizes you can get them here
www.victornet.com
AK
Course or fine. What is the difference?
In fractional (inches) threads there are two standard thread pitches NC (national coarse) and NF (national fine). The number of teeth, measured per inch (Teeth per inch (TPI)) vary depending on the size you are planning on using.
For example 1/4" fine is 28 TPI and coarse is 20 TPI. This following site shows the different sizes and TPI
Bolt Depot - Threads Per Inch Table for US Bolts
In the metric system threads are measured by the distance between threads, so you will see 0.5, 0.75, 1, 1.5, etc., which is the distance in millimeters between threads.
What is your application? Someone should be able to point you in the right direction for what you need.
AK