Those pics are worth as much as someone is willing to pay for them, I'm afraid.
May be a good thing, may be a bad thing.
That they are unique one-off prints makes them extremely desirable to the right SW fan, or fans of movie memorabilia in general. But - and I'm no expert - even if they were signed by one of the members of cast or crew, for example, they would not be worth rediculous amounts of money.
Your best selling point - apart form them being unique (I presume they are one-off prints), is that you know the story behind them and how they came to be taken.
If I was you, I'd try and find out as much as you can about why the guy was invited on set, why he took the pics, the details behind each particular pic etc - attach a bit of history to them.
Because, in the end, that is what gives them their value - the fact that they are of historical interest.
I dunno what kind of price you should put on them, but - like I said - it is just a matter of what someone is willing to pay.
If the right person sees them.
Deciding whether to sell them as a set or splitting them up is a gamble too.
You would think that keeping them together would make them more attractive to collectors, but the downside is the increased asking price (whatever price you decide on) is going to be a lot higher for one lot, which may put people off...
Whatever you decide to do, they are certainly nice pics...
🙂