Craft of the Month in the Mail

Check into Lowes and home depot building kits... I don't think they will send it to you, but you can buy thier build and grow kits (kids workshop kits) for about $7.- here...
Also I know that there are curriculum courses for day cares that will send you a months worth of crafts with supplies... Cost is PER child... So if you enroll one kid... thats all you pay for... places like http://daycarekits.com/index.html ... Not sure the age of your son... But they have things out there for all ages...

I have not used this myself, but plan to when my son is old enough!

http://www.kraftykid.com/category/craft-clubs

Sounds like fun!

This is geared towards adults:
http://www.creativewomanclub.com/

This is geared towards kids:
http://www.kidscraftofthemonthclub.com/

There are a lot of them I found, just google "craft of the month club"
and compare the crafts/prices and such.

http://www.google.com/#sclient=psy&hl=en&q=craft+...

we used to belong to the together time craft club. i'm not sure they're still around, but it was really fun. they would send a box with a nice magazine with crafts to do, facts about whatever was going on in that month, all the supplies for the crafts. we would make the craft then give them for presents.

Oriental Trading Company has lots of craft kits in their catalog.

Why not get some basic supplies like crayons, markers, feathers, googly eyes, paper bags, paint supplies... and google crafts suitable for your child's age group? ie. preschool crafts, etc. They even break crafts down by materials, seasons, type.