M.,
You are in luck that September is a huge month for large consignment garage sales, which should have clothes for your son. I've been hitting these sales this past year for my son and have found excellent deals. They have racks and racks of clothes in all sizes. Bring a laundry basket when you shop.
1.September 6-8 @ VFW Hall 1205 Ott in Olathe-www.whaleofasale.net
2. September 14-16, 2007 at the Overland Park International Trade Center (6800 W. 115th Street, Overland Park, KSÂ 66211)-kc.jbfsale.com/index.cfm?fuseaction=home.showevent&eventid=2006020318263939&siteid=2006020116561073
3. September 20-23 - Metro North JBF Sale - http://nkc.jbfsale.com/index.cfm?fuseaction=home.showeven...
4. September 22nd from 8:00 am till 1:00 pm. - Mothers of Multiples Garage Sale - First Church of the Nazarine, 11811 Stateline Rd (119th & Stateline)
5. OCTOBER 19-21, 2007 - Kansas Speedway, 400 Speedway Blvd., Kansas City, KS 66111 - http://shawnee.jbfsale.com/index.cfm?fuseaction=home.show...
As for clothes for you, my husband had found this website that looks like it has good prices: http://www.coboutlet.com/. I also think that Goodwill store on 135th & Murlen is good.
Good luck!