Wow, seeing these costumes brings back some memories for me... I recently left a position at a costume company. I actually worked with some of those costumes (the Wonder Woman one, for instance).
A couple things to keep in mind if you really want a certain costume for this year:
1.) Order early - this is the busy time of year for costume companies (duh, right? - the company I worked for did HALF their yearly sales in the six weeks prior to Halloween) and they may run out of your costume if you wait too long.
2.) The sooner your order, the better chance of getting a replacement if the costume you receive is defective or not the right size.
3.) You get what you pay for. The cheaper priced costumes tend to be of poorer construction and lower quality materials. If they have the same or similar costume in a deluxe, you might want to consider going with the higher-priced one.
Ah memories...
Have fun!