And it will never be updated, as I mentioned in the Dallas thread, we don't ask the creators.
Mark Brooks Mark will sign 1-2 items for free. After that he charges $5.00 per signature for items that are not being graded. Graded items are $10 per signature. As per Comics Sketch Art.
For other Comic Sketch Art guest please click on their info and then Event Info for their show rates. http://www.comicsketchart.com/artist-alley.html
For guests appearing from Scott's Collectables (Inhyuk Lee, etc) please visit https://www.scottscollectables.co.uk/ and look under Creators to see their pricing (it's in UK money so you may need to contact Daniel for American prices.
For Artgerm and Derrick Chew, https://artgermcollectibles.com/ you may need to ask the folks there what his pricing will be.