True, the MakiBox isn't out now but has a (slightly) bigger build area and does both PLA & ABS for $299. If you only want to do PLA like the PrintrBot, it's only $199.
this is debatable.
Makibox build envelope is: 150mm wide x 110mm deep x 90mm tall
Printrbot simple output is almost identical out of the box, being 4" cubed (meaning 101mm for each axis) so, your makibox has an extra 2" wide x axis, y axis is almost 1" deeper, but the simple has about 1" of extra z height. differences are negligible.
You can swap out some of the printrbot's rods, and a piece of monofilament (the x belt) and increase the x and z axis to 7.5" (or 190.5mm) which would allow for a much greater build volume. the kit to do this costs $65. You can't do that with a makibox. you would need to re-design and cut new panels for it's enclosure.
If you want to print ABS, you need to add a heat bed, not a major upgrade, as the Printrboard has heatbed output and an available port for another thermistor. or, you can just buy a junior, preassembled, with a heatbed and a 150x150x150mm build envelope, machined aluminum buildplate, plus it can be folded for easy transport; that's $699, but it has a larger output than the makibox. these machines are still open source, so you can cut your own parts, and build them yourself to make one for even less.
of course the main reason I wouldn't get a makibox is simple: It uses drive screws on every axis. a drive screw is great, for the z axis, which doesn't need to move all that fast, but on the x and y, this is a bad design, as you will get print inaccuracy from the wobble of the threaded rod, and your print speeds will need to be much slower (why do you think all other printers use some sort of belt and pulley arrangement on the x and y axis?)
once you run a few parts on a machine, you realize how critical your movement and extrusion rates are, at 100mm/sec, a 4" cubed print can take about an hour, depending on infill and layer height. if you need to print at 30-40mm/sec to compensate for wobble and the step-rate of a threaded rod, well, let's just say you'll be waiting a while for that same cube to print.
But that's just my personal, experienced opinion.
I watched this video of a "supposed" live print of a bunny on the makibox. Funny, I don't hear the steppers running, and the video is awfully jerky (like it's been sped-up), still, to print a hollow bunny (with no real infill just hollow internal supports) it took 2+ hours to print:
Not trying to hate on Makibox, it's an interesting design, and it looks like they've been trying to address many of the shortcomings, but nobody has one of these yet, and it ships from china, so until I get a hands-on, or enough people have given an unbiased review of it, I'm skeptical (a Printrboard alone costs $130, so they definitely aren't getting theirs from Brook, likely they're making their own knockoff to keep costs down).