Check out the new Formica colors. Some are beautiful and very practical for a bathroom. I think that is tons of $$ for a top.

Where have you looked for stones? Have you checked with granite/marble fabricators in your area? Most have remnants that might fit your top. Should be less than $500, though prices really seem to vary by region.

You might also check Craigslist.

It seems that 49" is a standard size for vanity tops. Have you already confirmed that you can't use a standard size -- if not that one then the next size down, 36"?
You can get ready made stone ones in this size, with built-in sinks if you like, on ebay and in other places.

Also, here's an auction where they want to get rid of a top and will cut it down for you.

Where there's a will there's a way! If you really want stone you can get it for less.

Kashmi mentioned checking on fabricators in your area. I found one fairly close to me who makes lots of vanities and can do it for far less using popular stones that they stock -- you don't pick your slab. If you can use standard cuts for length and number of holes you get an even better price.

I had formica in my last house, and amazingly enough I never ruined it with cleaning products or nail polish. I was always afraid that I would hurt it, though.

Here is a link that might be useful: ebay -- will cut down to your size

I was also discouraged by the $500+ for granite vanity tops. So, I'm going with a custom cultured marble. They come in a lot of different sink styles now, a few solid colors, and a lot of imitation granite and onyx colors.

I just had a handyman install my custom cultured marble shower and I love it. It is substantial and smooth and clean and shiny (I got gloss white).

A local company manufactured mine, and I visited the factory showroom before deciding. It had to be ordered from an intermediary, like Lowes.

Another vote for cultured marble.

You can get the look of stone by using stone tile. Set the tile on the diagonal so seams will show less and lay it with vey tight joints so almost no grout shows. It will look good but cost lots less.