I purchased the Gaggia base off of Ebay in the UK, so it cost (with shipping) £25. I bought because I knew I would be purchasing Gaggia machinery, and because it was a steal at £15 (WholeLatteLove carries it for $69). When I received it, it was in excellent condition (probably only slightly used), especially for a base made of plastic. So, the construction is very strong. It's black, sleek & simple, with a large indentation on the right side for the espresso machine and another smaller one on the left, slightly raised side for the grinder.
I've never owned a base of any kind before, so having the knock box is a miracle for me. I always used to knock pucks into the sink, and I would have to spend time in the morning cleaning that up (which I hated). With the knock box, I only have to rinse it out after disposing of the grounds in the trash. It pulls out for use and then hides away neatly, in case I don't have time to clean it out before work. The only problem is it isn't quite deep enough, so sometimes I'll push the box full of grounds back into the station and an edge will hit a mound of used grounds on the way in. Also, the knock box can be little bit difficult to pull out and push in and can get slightly stuck.
I purchased my Gaggia Cubika first, which of course fits the espresso machine side perfectly. I then ended up purchasing an Aerolatte Burr Grinder, which ended up fitting the grinder side almost as well (the grinder base is slightly longer than the indentation, but not so much as to be a bother). I do wish there was just one extra compartment for storage of the tamp, a brush for cleaning the grinder, and other small accessories. There's a slight bit of room between the espresso machine and the side the grinder is on to put these things, but it stops me from pulling out the water tank on my machine to re-fill.
If you have a Gaggia set-up, this is definitely a must have for your home espresso bar. Perhaps you'll get lucky and find a good deal on one on Ebay.