First timer please help

I am just getting into collecting, and have an opportunity to buy some signed screen shot type photos of Mortal Kombat the firat game, signed by the actors who portrayed them. The seller is asking me to make an offer, I told him I didn't want to insult him with a low offer, as I have no idea what there value is. He said he would not be insulted just make a fair offer. I guess the help I need is, can you guys gimme an idea of what is "fair"? Thanks a bunch!

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And if this is in the wrong area I apologize, I am still learning where things are located and where to look for them.

What did you have in mind yourself?

Haven't a clue, I would guess $10 or so each. I have tried searching to find what something like these would be worth, but no luck.

Where are these being sold is the main question?
If it is in eBay, then I would worry they are fakes. Something like 90% of autographs on eBay are said to be forgeries.

It is through a Facebook group.