Fraser Bath Vanity, $499 includes vanity, top and sink. Faucet extra. This may be too modern for your taste, but it could be a good option for the downstairs bath. Looking at your plans it may be too wide. I am going to guess we need to find a 30" wide model.
Home Decorators Collection Hanley 23.63 in. Vanity and Vitreous China Sink in Charcoal Grey with Porcelain Vanity Top in White