Where can I find Krumpholtz's Harp Sonata in G in mp3 format?

On my local classical radio station, I heard this beautiful harp sonata by Krumpholtz. I did some research and found that it is called Harp Sonata, Opus 13, No. 4 in G major. I found a CD with that, along with Krumpholtz’s other harp sonatas, on Amazon; however, only two copies were available, used, for $55 or more. I can’t seem to find the sonata on iTunes either. Is it too obscure, or is there another online resource I could search to either download or buy the song?

I know this question may be a bit too specific, but I thought I’d give it a try. Any suggestions are greatly appreciated. :)