It sounds pricey but it depends on how they're finished and the detail and finish on the inside of the cabinets & drawers.

Except for the wood, is what you're describing like the pic below?
If you're trying to save some money, I'd take a photo of what you're wanting and visit some of your local cabinet makers. I found one a couple of years ago thru Craigslist who does beautiful work at competitive prices.

Here is a link that might be useful: {{!gwi}}

$400-$500 a linear foot isn't at all out of line with a premium cabinet company. You have 6 drawers, which is a lot of % of the quote. You'd bring it down if you combined the 12" and 18" drawers into a 30" drawer. You'd gain in usefullness as well. A 12" drawer doesn't hold much of anything. Alder is a premium wood, although not as premium as cherry or mahogany. Slab doors can be an expensive choice as well, depending on how it's constructed. You could potentially shave a bit off of the quote by choosing a maple and a veneer slab, or veneer shaker style door. Oak would be the cheapest wood. How you finish off the cabinet's visible sides will impact the cost as well. If the vanity is in an alcove where no sides are visible, that's the cheapest, of course. The next would be a skin or thin veneer panel, and the next would be a solid beauty species plywood flush integrated side. You could also have a cabinet door to cover the side (would need to be over a skin or flush finished side) or some lines offer an integrated cabinet door side.

I'm sure this quote included toekick, quarter round, scribe molding and a touch up kit as well. Those would be adding around $200 to the quote, but you can't skip ordering any of them if you want a decent job.