I use this one from Harbor Freight and I like it a lot: 500 Lb. Capacity Deluxe Cargo Carrier
I actually bought another one that I plan on modifying to attach to the top of my roll cage when the top is off.
To see images of it, click on the "Support/Download Manual" tab and open the PDF file there.
I don't really think you have to worry about spending extra money on a hitch cargo carrier, they are pretty basic and I can't see it being all that different from one to the other. I do have to say that it was a pain in the a** putting it together, and that it does look slightly crooked (1-2 inches lower on one side), but it works for what you need it for. I know that a lot of people have bought hitch carriers over the years and spent around $200 for them and sell them after a couple of uses. All I use this for is to get me from home to my campsite where I take it off and leave it.
You are probably right about using a hitch extender to clear your spare, but Harbor Freight has those too