Should we buy used 5th wheel

Well Gloria there are a few things you need to learn. What is your tow vehicle? Is it big enough to tow at the trailers GVWR (not dry weight)? What is the TV cargo carrying capacity? Can it handle the pin weight? Make sure you have a big enough truck to handle your trailer. Since you don't have any experience with 5th Wheels. Then you need to do some studying on line, talk with others, increase your knowledge. Once you have gained knowledge, what is your budget? Are you going to keep your present house, or sell it and use proceeds to buy RV? Have you ever done anything like this? If not you may want to rent for a week or two to see if you like it.
I have owned 5 RV's and learn something new all the time. Learned a couple of hard lessons in the beginning and was lucky it had some knowledge of repairs and if not where to turn to when needed. Good luck and continue to troll the forums for help.