AK Anne Klein has a very similar pump which won't break the bank at $45.11 (on sale). They are leather instead of satin but I think they are still a great alternative for less. Click on the image below if you're interested in purchasing.
Nine West also has a similar version of these shoes (although they have the extra side instead of being totally cut out on both sides like the other two options), which retail for $79 and come in natural, black, or fuschia. Click on the photo below if you're interested in purchasing!