Pawn Stars is heavily staged and scripted.
If you've ever actually been to the store (I personally haven't, but spoken to two friends who have and there are numerous recordings of a walk-thru during "normal" business hours), it's completely different then what you see on the show. First, 90% of the store is filled with Pawn Stars Show Memorabilia. Things like t-shirts, bobble heads, those silver coins with the Old Man's face on them, etc. They have a bunch of things you see in the show, but rarely actually sell them for the inflated costs. The store itself is usually PACKED full of people, where you can barely even walk around, let alone see anything. The principle characters are almost never there. One friend saw Chumley, but he was only there to sign autographs. And they don't really buy anything, at least from 'normal people'. There is a good video of someone taking in some very expensive and rare item, only to be summarily dismissed by one of the staff with some generic "sorry, not interested, we're not buying things right now" line.
Another friend who was in Las Vegas actually ran into one of the "sellers" on the show at a bar. He was some musician who came in to sell his guitar. My friend spoke to him and said he was paid by the producers and everything was scripted - he never actually sold anything.
We watch the show and enjoy it, but mostly for the limited history information on some items and entertainment value. But the transactions are not based on reality.
If you ever watch Hardcore Pawn, that's certainly more like your typical pawn store as far as the clientèle, merchandise, etc. However that too is also completely staged with fabricated stories, people, etc. They also screw up in the editing room and give out way too much confidential information in some of the clips if you pause and zoom in. Things like people's home phone numbers and office extensions. Hell, one guy's social security number and address were on the screen for a split second before they blurred it out.
In any case, you need to take any of these reality shows with a huge grain of salt.