doesn't designspark tie you to their fab? expressPCB also has a free piece of design software, but it ties you to their fab. kicad sort of is what it is. it's a weirdly architected, very buggy layout and netlist editor. eagle is the industry standard but has a correspondingly high price tag. even the individual student professional version is 820$.
however, the audio folks have been using eagle anyway for quite a while. there are a couple tricks. first, design onto multiple boards. yes, this is difficult for a keyboard layout, but keyboard layouts are mostly cut and paste, and no one said you had to put the keyboard matrix and the controller on the same board. second, the pricing is set up to get you to buy a number of seats. i am open to banding together under the geekhackers banner to standardize on eagle. at 10 licenses of layout + schem (autorouting = bleh), we're looking at about 340$ per seat. have you seen the pricing on solidworks lately? this is pretty reasonable comparatively.
the really big benefit of eagle is not necessarily how flashy or user friendly it is but just that it's extremely standard, which makes collaboration on a board easier. otherwise, kicad is probably the way to go. diptrace, if it seems to work as well as eagle and is more intuitive to build and use than kicad, hits that same price tier at half the users.