Looking for an Eames dining table base...  

Sometimes eBay
is the place where you can find someone selling a base without a top.

Yes, eBay
Is where I got mine.

Sometimes...
you have to buy an entire table to get the base you want.
Which Eames base exactly are you looking for? There are a few.

Don't know which one you're looking for...
But I have a contract base I'd be willing to part with. It's vintage, factory black. There are a few different Eames table bases, mind.

Contract
Contract bases are fairly common on eBay. Try MetroRetro in Texas - they usually have 4-5 at any given time. I found mine on Craigslist for $25 - so it's worth it to do some digging. I didn't see much difference in mine other than the patination of the aluminum foot. If you want super shiny aluminum buy new - it's almost impossible to polish those things out without specialized equipment.

I have seen Contract base...
I have seen Contract base and Segmented base. But what I would really like to get my hands on an all-aluminum base that has four pillars forming the centre stem. I have only seen it with a marble top. I think it is called La Fonda. Is it still being made now?

The LaFonda base is not available
in the US, in any size; Vitra has the coffee table available in Europe. It's a smaller base than the dining room table base, which I don't believe is available anywhere, anymore.
Its lack of availability raises the price on eBay.

670 base
But have you seen the table base that uses the same aluminum base as the 670 lounge chair? They sold them in black like the 670, or with white paint which I think is more striking. It is far less common than the other two bases you mention, but not as hard to find as the LaFonda base.

In europe you can also get...
In europe you can also get the contract base with black or white sides, matching the european lounge chair. There are also a wider version with adjustable feet for large tops.

Those Vitra ones are...
Those Vitra ones are nice.
Is the Eames 48" wood veneer table on segmented base stable? I really dislike unstable tables like the Saarinen tulip ones.

I had one
48" round top on segmented base... I think that's the only way it comes these days. Stability is fine.

Unstable?
Since when is a Saarinen tulip table unstable? Do you eat at your table or dance on it?

The Saarinen marble top tulip...
The Saarinen marble top tulip dining table wobbles when there are a few people sitting around eating steaks.

Table or.....the floor? ...
Table or.....the floor?
Do the marble roll test.