Sometimes a song gets stuck in my head, or I want just a few songs from a particular group. If it's just one, I'll pay the 89 or 99 cents from Amazon MP3 downloads.
However, sometimes, there are just a few key songs that I want by a particular group...more than one but not enough to justify $10 - $20 for a greatest hits collection.
Enter the Rhino Hi Five! These are mini greatest hits compilations available from Rhino records (http://www.rhino.com/shop/crossgenre/hi-five) or places like Amazon mp3. The cost for a collection is usually $4-5 and you get the key songs that made the artist famous. Rhino offers high quality mp3's and also offers them in lossless formats so you can create a higher quality CD. However, you do pay more for those, and I find the mp3 to be more than satisfactory.
Check them out the next time you want just a few "old memories."