Go with whatever suits what you want to do. If you are flying very few hours then the cost of the TT straps for the JR may be a bit of a burden. While a 500 is faster than a JR don't believe everyone that says they outperform them all the time. Remember that when people talk max gross fill with fuel then say a 500 performs better, they have forgotten that you have 3.5 hrs gas in a JR and 2 max in a 500. Other than that maint on both will be similar, depending on what you get when you buy. The 500 does pull more power out of the same engine as the JR and generally they go through engine parts quicker. If you are only ticking off a few hrs a yr then engine O/H will be the least of your concerns.
Parts for 500 should't be a problem anymore, and they have never been a problem for Bell
As someone else has said if you are going to take a couple of adults, with a bit of gear, or maybe some kids, then a 500 could do it. If you want 5 adults comfortable with gear in the boot, you can't beat the JR. Also initial purchase price you should be able to get a far better JR for the same money compared to a 500. Should, not will, and you can get screwed not matter what you buy. Also the reason that there are so many JR's for sale is that there are so many out there. I don't see many ferraris for sale compared to fords, bit of a silly comparison really.
I doubt that a private pilot would get a 500 into any smaller area than a JR, as they won't go anywhere that tight.