I guess it would depend on where you live, how high your caliber as a skater is, etc. Plushenko I don't think accepts any and everybody but he does accept more people than Eteri does because he needs to get his coaching running. I don't think I've ever heard of Eteri offering a summer camp. Maybe Sambo 70 but it would never be with Eteri unless you're Sasha/Anya/Alina/Zhenya/etc. level, but I think Sambo 70 tends to have its students working throughout most of the year, with more off a week-long break in several different places sort of schedule. That's how it is with a lot of athletics, because too long of a break leaves one struggling to catch up.
I think with Eteri at least she spends a lot of the summer choreographing for the little ones or assisting Daniil with such choreography. I think her main focus is on her skaters that determine her reputation as a coach rather than earning a bit of side-money by offering summer camps. It certainly would be a wonderful experience if she did, but I don't think it appears to be that way.
Plushy has done camps. I'm not sure what his policy of accepting pupils on a more regular basis is, but there is some contact info here - I don't know if it helps: