Have you considered going to a stone yard and looking at their remnant pieces? They usually have a large selection and the price is not as high as you would think.
You would have to already have a table and either use the new top on top of the old one, or remove the original top and replace it with the granite.

If the tile top is meeting your needs, is there a specific reason why you want to changes it? I'm asking because last year we bought THREE different table sets in various price ranges and regardless of price, all three were junk; especially when compared to the 20 year old 200.00 farm table we already had. We ended up returning each and every set we tried and I decided to refinish the table I already had (and loved) instead. As much as I enjoy getting new furniture, I really couldn't be happier with the choice.

We had used the table as a workbench for years while working on the house. It was in pretty bad shape and had definitely seen better days. The chairs are new as the originals to the set were long gone but there are lots of chairs to choose from in a really affordable price range. Sanding was a challenge but all in all, it wasn't as hard as one might think. If this appeals to you, post a picture and maybe we can help you with suggestions.

I post these pics a lot so sorry if it's a repeat for you but it does show you the potential your table might have. We saved a lot of money doing it this way too. The chairs were about 300.00 and the stain/varnish was under 50.00.

Before:

And now:

Glass can scratch, but it won't dent or absorb stains. So you can try a glass topped table, or a traditional table and get a piece of glass cut to protect the top.

Or you can buy padded vinyl and cut it to fit the table top and then use table cloths or not when he's working.

I'd also explore why he want to work there instead of at his desk...is it lighting? Electrical access? work surface? I was always taught in business that the way to move people toward change is to eliminate the negatives. If you could fix his work space, then you may be able to save the table.

There are two of them on the Sears site. Here is one of them.

Here is a link that might be useful: sear's granite top table

I don't have any other suggestions but I could have written what you wrote! My dh likes to work at our table instead of his roll top desk...and we have a big house, there are several large rooms I could convert into a beautiful office for him but he likes being in the hub of things.

My husband liked being in the hub too, which I could really appreciate at first. For his birthday, we got him a nice reading table which he loves; we even placed it in the living room where he is in the mix. Well, the next thing I knew, one of the computers and a 22 inch monitor was on it so he could "play" while I watched tv. And of course that meant having to have a better chair (an office chair no less) for comfort. Then a couple of months ago, he started studying there too and now the office upstairs never gets used. When it comes to our living room I'm feeling a bit defeated anyways and his table really doesn't help. :c(

If you don't want to use glass, you could buy a plexiglass blotter. They are lightweight and could be stashed under a couch or on top of the dryer when you are having guests. It would protect your table top the rest of the time.

Here is a link that might be useful: Plexiglass Blotter