What possible reason do you have for even considering it then?  Because it's cheap?
Don't get me wrong...I like SI. I just am not sure I would come back for more enough to warrant it taking up the space.  I played lots of SI on the 2600 when I was a kid.
I am thinking that buying it for $50, cleaning it up a bit, repairing the damaged corner and selling it might be whorthwhile.  Perhaps with some art, a marquee and a good cleaning this project could subsidize a full scale mame cab in the future.
Another temptation is that it's close...most of the cabs in my budget are over an hour or four away.  this is like 5 minutes.  And it is cheap so why not? (other than the space...LOL space invaders... 

)
Ok, bad .  

Also any arcade cab is just plain 
cool!. I have so much fun researching and tinkering that the gameplay might just be gravy.
I hope that settles why I might want it.  I guess
Besides if it's a knock off I could consider selling the board guilt free and mame it.  I kinda like how it looks...