most are probably cheaper.
Wanhao have got some large volume machines out as have the dutch Builder firm.
And don't forget there are some pretty big delta machines around that would give the same build volume.

Wanhao duplicator 5=305mm L x 205mm W x 605mm H for about half the cost of the z18
Big Builder=220 x 210 x 664 mm -= a bit smaller - but it does have a clever one nozzle dual extruder going for it.
Both the above build a good bit taller tha the z18 if not quite as wide.

What I'm basically saying is the makerbots are massively over priced for what you get - so would you genuinely buy another one ?