Track Down Purchases v2.3 will examine each track in the entire iTunes libraryor a selection of tracksfor items purchased from the iTunes Store (audio, video, and audiobooks) and then sort them by either the purchaser's name or account ID into discrete playlists, eg: "Purchased by Tom Ryan" or "Purchased by firstname.lastname@example.org".
Purchaser information is gleaned by examining the track's local file (purchase info for iTunes Match tracks in the cloud is inaccessible and cloud tracks will be ignored), which, depending on file location and access speed, may take as long a second per track. Just sayin'.
This lateset version fixes a problem for some OS X 10.9 users whereby the script would hang once engaged.
More information and download is here.