If you have a granite fabricator in the area, they generally have remnants from large jobs which they sell for projects like yours. I've replaced two single vanities and a double this way. Singles Good luck.

You need to find yourself a nice prefabricated granite shop. They import the counters already cut with an edge and back splashes polished. All they do is cut off a piece for you in the length you require, put in the undermount cut out, attach the sink and polish up the edges. It is a very affordable way to get granite for a vanity. They just charge you for the amount you use. Do a search for prefabricated granite in your city.

The ones around here have tons of colors to choose from so you have lots of design options. Often they will also have discount sinks but if not they can use a sink you buy to cut the under mount opening. My prefab shop charges just $50 per sink for white or bisque oval or white rectangular. But I wanted bisque rectangular so had to find them myself. I just bought my sinks at Mr Direct for $70 each including shipping. http://www.mrdirectint.com/ to look at them. I bought the sinks through e-bay which had slightly lower shipping so saved about $10 over buying from them directly.

I got my faucets at Express Decor. Home Depot and Lowes had nothing interesting. I got this one for $150 each. http://www.expressdecor.com/kraus-mil-1202-millennium-single-lever-basin-faucet.html for my master bath. I see they are running a 10% off coupon on it today. Even though I ordered it yesterday I saw in my e-mail they credited 10% back on my card today. :-)

When we do our guest bath I'm getting this one.
http://www.expressdecor.com/kraus-kef-14801-pu11ch-fantasia-single-lever-basin-faucet-and-pop-up-drain-with-overflow-chrome.html

And probably this one for our upstairs bath.
http://www.expressdecor.com/kraus-kef-14301-pu11ch-unicus-single-lever-basin-faucet-and-pop-up-drain-with-overflow-chrome.html

In my case I'm getting my counter tops from a prefab shop but having it cut from a prefab island. I am getting a specialty edge that is known as a broken edge but still saving about a thousand off what it would be to buy an inexpensive slab and have my counters cut out of it.

Last month I walked into my local granite countertop fabricator, carrying the square sink I had purchased online. They had dozens of remnants of granite and quartz to choose from. They took me back to the warehouse and let me look through them and choose. I chose granite, for $182 I got a 36" top, polished edges of my choice on three sides, with my sink undermounted and the granite drilled for my faucet and a 4" backsplash.

If you get flyers in the mail that list different businesses, look in those. The countertop shops often run specials to get rid of their extra pieces.

We actually offer a Customizable website where you can customize your vanity exactly to your needs!

Check it out!

https://www.grifform.com/custom-lavatory-vanities/