I am always wary of 'hall of fame' inductees, and claims of 'many full contact knife fights' would indicate that he is a multiple-murderer (winners drip, losers gush), but outside of all the hype ans silliness, what you have appears to be an escrima based form of JKD, similar to what the MKG, Dan Inosanto, and the KFM guys offer.
I prefer such stuff to be presented without the 'guff', but there is no reason why it shouldnt be a good seminar. I have attended Rick Faye (MKG) 2 day seminars when he guests at our club, and the cost is around £40 for 2 x 7 hour days.
I think that is really cheap, but on the flipside, your friend should be wary if the price is crazy- it doesnt indicate any greater quality, just profiteering.