The result will be the same. The cheap product will have less quality, but treat it gently, it will last for long. I have had a Jes extender for many years, and I know that original spare parts for it is expensive. I did buy me a cheap copy from ebay - certainly the same,as you will find on amazon or other sites. Was it a difference between the two ? Yes there was. The cheap one had the option to use the strap in addition to the noose. ( the Jes I have is old and is only for noose). The cheap one were a little more «flimsy» -where the rods connects to the base - but other than that, it did the extending just as good. Mainly, I still use the Jes more, and keep the copy for spare parts, and extra rods if I will need one.
If you are new to extending, buy the cheap one, and find out if extending is for you, and if you like it, and your penis are up for it, the you can consider buying a more expensive one for the long haul.