what is machine robo mugenbine?
 

is it a super sentai?

No.
Machine Robo Mugenbine is based off of Machine Robo Rescue, which is in turn based on Machine Robo, which is the basis for the Go-Bots series.

are they anything like super sentai robos? because if there cheaper and are still as cool as super sentai robos then i might collect those!

Sort of. If I recall correctly, the Joint Gattai series can work with Mugenbine. So a Junk Stag, Air Leon and Joint Gattai ShinkenOh can all swap parts and combine. Though, there aren't many Joint Gattai figures.

But if you mean "are they like Megazords?" then no. To quoute TJOmega, it's "LEGO for Giant Robots."

That depends.
The original "DX" series of Mugenbine is very unlike Super Sentai. There's one base figure, with a bunch of parts that attach to said figure to make it look like other things. All the pieces are interchangeable with other "DX" Mugenbine, which brings up the whole point of the line: nearly infinite customizability and interchangability.
That said, the more recent candy toy series is a lot more like Super Sentai. It usually features 5 or so components that combine into one big robot. They still interchange like the "DX" series, but there's a bigger focus on the Sentai like nature of them. They're pretty similar to the Super Sentai Minipla, actually.

but are they cheaper then super sentai robos? and are there any reviews of the dx series on youtube? because i want cool combining robos and these seem sorta cool so what series is the largest/ most playable

Baltmatrix on Youtube, and Tokunation Member, has excellent reviews of alot of the Mugenbine line. I'd start there. Just type in Baltmatrix Mugenbine

And they can be cheaper, and alot more fun.

when i type in gao king on ebay (as in from super sentai gaorangers) it comes up with super robot chogokin king of brave gao gai gar choryujin. what is that?

Robo Rescue, a Toku show like Sentai.. but not.

If you want review of Gao King use Baltmatrix, he did a nice one of alot of the Gao mecha. SH Figuarts goto Peaugh.

sorry i edited my above post before you posted