Did you know that Monday and Tuesday are the biggest days of the week for online costume sales? Maybe it has to do with post-weekend day dreaming… “I was just thinking about what to be for Halloween over the weekend. Damn Mondays. How about I put this TPS report away and look at costumes online”.

If you’re feeling that post-weekend Halloween itch then be sure to grab one of these coupon codes first. These are all good for the entire season so there’s no rush. Check back for the really good limited-time sales which will probably start showing up in early October. If you know of any Halloween-related sales or coupons (either online or at a retail store) please share them in the comments.

UPDATE: Here’s a new time-sensitive offer from Buy Costumes: Get 10% off your order with code HAUNT10. You can also get free shipping on orders $60+, and no coupon is required. Expires October 1, 2007.

• Buy Costumes: Most orders ship the same day, they have the cheapest shipping, and their selection is absolutely unbeatable. Use coupon code FRANKEN5 to get 5% off orders $65+
• Extreme Halloween: Family owned company offering Halloween costumes over a network of 12 sites. Use coupon code 10CJ to get 10% off orders $75+, or code 15CJ to get 15% off orders $100+.
• Spirit Halloween: Huge selection in their retail and online stores. Use coupon code 20Percent to get 20% off one item. You can also combine that with coupon code FreeShip49 to get free shipping on orders $49+.
• Retro Candy for Halloween – Old fashioned candy from the 50s, 60s, 70s or 80s… Get 5% off any order with coupon code 00224 (*This one expires Sept. 30th)