I scanned in a lot of mostly class 2 & 3 piano accompaniments and created practice MP3 recordings for my former students to use. (Retired now)
Anyone is welcome to have all of the files I created that are still on my Google Drive. I've compressed the folders containing the files to make it easier to download all of them at once. There are Sibelius files as well as Music XML files that Finale and other notation programs can open. The original folders showing individual files are still there too.
To create accompaniment recordings, simply mute the solo lines in the files and create a recording of it with your notation program. Tempos can also be adjusted and these files are still fully editable.
Link to my files you can access: https://goo.gl/RyjYbp