I'm thinking about selling my 629-6

What's a fair price to ask ?

the revolver is a nice shape, a few character marks.
timing, endshake, ect., are nice. no issues or problems with the gun.
box included.

You should be able to get $600 for it.

or 500

Outright private sale you should have no problem getting $500 to 600, at a gun show on a dealer table your gun would be priced at $750 to $800 depending on age & condition. I have one dealer in my area selling a new 629 for $850 but everyone else is a grand or more, and older models without the key lock fetch a premium. I've been hoping to stumble on a bargain mod.29 for a while, but key lock or not I don't  see them for under $600 around here. If not I may just plunk down for a new Combat Magnum for $800 but I had a mod.29 years ago and those large frames with the red ramp/white outline sights are the best for range use.

In my area a good price would be $500. Where are you located?

$600 ftf no problem.  $300 trade in.

LOL

Model 29s and 629s tend to vary in price based upon the region. Some parts of the country they seem to fetch $100-150 more than others and vice-versa.

In my region (the Rocky Mountain West) a 629 with a lock is a $500-$575 gun. Without a lock, and with a hammer mounted firing pin, you can add $150-$200 to the price. A nice older blued Model 29 such as a dash-2 it's easy to start at $800 and go up depending on condition, accessories, etc.

I have a new in presentation box early 1970s Model 29-2 4" that I was recently offerred $1300 for and declined. NIB 29s are increasingly scarce and prices have really climbed in the last 10 years.  Good luck with your sale, if you choose to do so.

Curious.  Why LOL?

LOL, because when you walk around a gunshow every vendor calls you over, looks over what you're carrying,  and tells you what you have is shit.
and only worth $300

If you want to see what similar guns are selling for, you can track actual sales on gunbroker. A nice 629 like yours should bring $600 IMO. You won't get a good price at a gun show because everyone is looking for a great deal.