There's an archive of musical instrument samples at this site: http://theremin.music.uiowa.edu/MIS.html
. It covers most of the orchestra, along with guitar and a few other instruments, and even has balloons popping and sticks banging together.
A brief look at a few directories says that these are aiff files, and some of them are very large. A closer look at a couple of files finds a 96kHz sample rate, and a lot of subaudible noise. I would imagine that there's substantial effort between these files and the sets of samples that you want. But, the data exist, and are available free.[Edit: Spelling]