Harbour Freight has a great buy on the hitch mounted bed extender. On sale for $22.99 plus a 20% off coupon in their flyer. Net of only $18.39 plus tax. I picked one up today.
You can join their club and they will give you better prices than the flier coupons. Usually a few bucks less. You can join online. I highly recommend it! If you work on your own car, you are always needing some tool you don't have and will not use a lot. HF is a great place to get them CHEAP.
I bought the bed extenders from HF several months ago and they work really well. I paid 18 something. My neighbor paid almost a hundred for his and mine are just as good.