The dress is from Target, and comes in pink and turquoise! There were some up for sale here in the "products for sale and wanted thread", but I don't know if they're all gone now.
They have them on ebay too, where they are generally overpriced
and referred to as "juicy" dresses, since they are the same velour material. It's extra sweet, with two little crocheted cherries dangling off.
OH, and around here it's affectionately nicknamed the "Lola" dress, b/c the first doggie to show it off was named "Lola" (and she really does wear it best!)