The official Pack 1 uniform includes:

Cub Scout Shirt (with required patches)
Neckerchief
Belt
Hat is optional
Cub Scout pants are not required, you may wear blue jeans.

Patch placement diagram (requires Adobe PDF viewer)

Sources for Uniforms & Supplies

The Scout Shop

Brickyard Plaza, Route 9 Westbound, Southboro
A fast way from Mendon is to take Route 495 North to the Mass Pike East, and get off on the Route 9 exit. Then, go west toward Worcester and the Brickyard plaza will be on your right.

Online Scout Shop

ScoutStuff.org