As far as I can work out, the original prototype model is completely different to the probable production model.
Even though they are saying that they can deliver 3000 units a month in September, I am not sure what they are offering. They say the enclosure is optional, but if you look at their most recent prototypes with a vertically moving printbed, and the printhead on a moveable X-Y axis, it looks like the enclosure is essential as part of the structure. All the hardware is mounted at the top of the enclosure.
Have they still not made a prototype of the actual production unit yet? Test prints from prototypes built from $300 of parts mean nothing if the $99 production units will be a different design built from much cheaper hardware.
For the $99, they have to supply 4 Nema stepping motors, a 12V 20A power supply (the minimum as they offer a heated bed option), probably an Arduino compatible RAMPS board, a wifi board, all the rods, screws, bearings, E3 extruder clone, temperature sensors, X, Y and Z limit sensors, copper wire and print bed. It is a lot of hardware for $99.
Then I assume with the left over money, they have to build, calibrate, test, and handle all the after-sales issues.
Since they are still in the early prototype stage, I think you can forget the delivery date.
The truth is you will want to option the printer up so it can print materials like nylon and PETG so you are looking at a more expensive printer. By the time you add shipping, it is getting closer to $200.
Definitely either buy something proven and available in the market today, or wait until they have their "3,000 a month production line" fully running. The $200 kits on the market now, like the Tevo Tarantula and the other Prusa i3 based designs are perfectly usable 3D printers with heated beds and 20x20x20cm (or more) print volume. They will require many hours of work building, and probably upgrading with new stronger 3D printed parts to be really useable and safe, but you can check them out on Youtube and you can buy them today.