Hi nikki, I've been selling dishes for about 20 years (and I am a supplier to Replacements) and it's my experience that not many people purchase entire sets of dishes over the internet. More often, folks are looking for just one or a few pieces to add to their collection.
There are two ways to look at the thrift store price. First, as a retail price: if you were buying the dishes for your own use, then $100. would be a very reasonable price. But, looking at it as a potential reseller, then I would say that $100. is far too high. For the pieces you listed, in decent condition (which means no scratches, no nicks, no utensil marks, no stains), a price of no more than $50. would be more appropriate.
Good luck!