There are several threads discussing whistle keys and applications for different keys, but little is mentioned about Eb. Some makers do make them, so what are the applications and who has one?
I agree there have been some excellent and really helpful threads about this topic lately, for which we are VERY grateful.
We have an Eb that was made by John Sindt (the same headstock also has a D tube.) We love it.
My kids are in middle school band. Anita’s alto sax was in Eb and we got it as an experiment to see if Wes could use her sheet music.
The Whistle Shop has a great chart that will show you what notes they play: http://www.thewhistleshop.com/misc/fingering.htm
WhOA not withstanding 
I can see that we are going to keep acquiring additional keys and ranges…
Yes, the Generation Eb is very affordable. Burke, Overton, Copeland, Sindt and others offer them in their standard line.
Some players probably just like the key of Eb for its higher, brighter sound. Mary Bergin plays Eb on some tracks of her Feadóga Stáin recordings. The band Dervish are notorious for tuning up a half step, where Eb whistle substitutes for the role of the D. It might also be used for playing with band instruments pitched in Bb and Eb, with Bb fifes, etc.
It’s also perfect when you want to hog a session with your own unique whistle stylings and keep your riff-raff fellow musicians from joining in. 
Some places have Eb sessions just because Eb is fun to play in. The fiddles just tune up a 1/2 step.
Some famous fluters play Eb flutes on their Cds. The Wooden FLute Obsession CDs have several Eb tracks. Having an Eb whistle makes it possible to play along with these tracks and learn the tunes.
Some church music is in Eb as well.
Doc