Here is a recommended boys equipment list. 

There are several online stores:

lacrossemonkey.com

Universallacrosse.com

Lax.com

lacrosseunlimited.com

Sportstop.com

Helmet:

Type:

-Cascade CPV-R $139.99 (+stickers)

-Cascade CPX-R $199.99 (+stickers) this helmet is a more advanced model but is only offered in an adult size. The color options are the same. 

Colors: (if you want Knights colors, otherwise, just get plain white or grey)

Shell (forest green)

Face mask color (black)

Visor (yellow)

Chin (yellow)

Chinstrap (black)

Mohawk decal (yellow)

Back decal (yellow)

Gloves:

Any make, any size in white. If your son has been playing at least one season we recommend getting a mid level priced glove ($60-$110). More expensive gloves are typically meant for high school or college. 

Arm pads: 

Any make, any size in white. Kids typically match glove and arm pad brands. 

Shoulder Pads/Chest protector:

Any make, any size, any color.  We recommend something inexpensive here as hard checks are allowed in our league.