There are a couple of two-disc anthologies from her time at Columbia (with less overlap than you would expect, about half the track) which are very inexpensive. The first, as you can tell from the title, is a little broader stylistically, the second a little more focused on pop/soul. I prefer the second. For all the things Aretha was, to me she was not a jazz standards singer. BTW, the Amazon and ebay crowd are trying to cash in on these, especially the second one, but thye are still low-priced on discogs. They aren't great musically, but will certainly give you an idea of what she sounded like on Columbia.