Some clarification is needed to JohnInKansas' first post regarding playing with bluegrassers in the key of D. He says the Eb saxist must add 7 flats. This is the key of Cb which is the same as the key of B or 5 sharps, or 3 more sharps than the bluegrassers are playing. The Bb sax would add 2 sharps (not 6) and play in the key of E.

Look at the circle of fifths and find the concert/piano/bluegrass key. Then move 3 positions clockwise for an Eb instrument or 2 positions clockwise for a Bb instrument to determine the key each instrument would play.

Or take the bluegrass key and count down 3 semi-tones for the Eb sax, or up 2 semi-tones for the Bb sax to find the key each instrument would play in. Like John says "It's not really all that difficult once you get the feel of it." John must have been a tootler in a previous life.

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Mooh opened this thread wondering if the electric guitar is the new sax, then partially answered the question later saying "Brass is so expensive." In my area a used student horn costs $700-1000 while a student level guitar with a small amp costs about $200, so affordability is part of the reason for the saxes decline. The rise of Rock and Roll also affected the saxes popularity. A 12 year old acquaintance who played sax in the school band asked for and received a guitar for Christmas. The sax doesn't have the cachet it once possessed. Times and tastes have changed.