Friend Wants to Get a Celebrity to Skype into an Event

Hmm. I have worked with celebrity spokespeople and speakers in the past and even for a charity, they charge. The only time we got freebies was working with past celebs for a quick follow up three years later.
Your friend can find out rates by working with firms who set this up, but no they don't just forward it on. They check schedules compare the celeb brand to the type of conversation/request. Sometimes the celeb is never approached and it is nipped in the bud at the agent/agency level. They also take into consideration press. How much exposure will celeb get for speaking at the event. Typically Skype is not how this is done. It is a satellite feed. . . I have only seen Skype end in disaster and poor quality interactions with the audience/speaker.
I say, he should give it a shot, but don't bet on it unless this celeb is a friend.

They all have prices for this. Most celebs start at 3k. Contact thru their booking agent.

There is no harm in asking, so your friend should go for it even if one seems particularly unlikely due to scheduling. Make sure he uses the business contact information, not the fan mail address, and that approaches the agency in a professional manner.

Also double-check to see the people have set up a way for fans to contact them. The ones that have public email, Twitter, official Facebook, etc. actually do read their own messages. If the people he is thinking about have set up a way for fans to communicate directly, he can use that method. Again, professionally. He doesn't have to be formal but he shouldn't write in textspeak.

The purpose of his event matters too. Things that are most likely to get a Yes - something that will help others, like a fundraiser, or will be seen as giving back to the fans. In the case of a fundraiser, it would need to be something the celerity supports and your friend's legal/financial ducks should be in a row.

ETA: I saw your SWH. A fan event is fine, but if he is self-promoting then it is unlikely he can get someone to Skype in unless he's prepared to pay full booking price.

I'm so sick of the celebrity craze. Just enjoy the regular folk who are there and charge a lower admission. That will be great charity!

Hmmm, that never even would have occurred to me! He sounds like Michael Scott!
I'm with you, but please post a follow up no matter what happens - I can't imagine anyone agreeing to do it.

What an unusual question! I would ask, is the event tied to any charity? If it's a fundraiser for some charity and that particular charity is one that the celebrities have been active in previously, your friend would stand a MUCH better chance of having one of them actually say yes. It should be very easy online to find out which celebrities have supported various charities or organizations. And if it's a charity he can then ask if the celebrity will do this for free -- so the charity can keep more funds.

So, if this is related to a charity, your friend really needs to find celebrities who actually have shown some activity on the charity's behalf in the past. If he's going after random celebrities just so he can draw attendees by saying that famous person X will appear by Skype -- I think the chances are slim, especially as it's such a small event (250 people is not many).

Also, if he truly does end up landing a Skype talk with someone, he should be aware that celebrities often say yes to things then bow out at the last moment if something else comes up. (Learned that from a friend who arranged stuff like this for a large charity group.) He should have his speech ready to explain that, just in case someone says yes then backs out too late for him to find a substitute.

They all have prices for this. Most celebs start at 3k. Contact thru their booking agent.