It is easy to remove the Lagun table mount leaving behind a flush bracket.  I doubt I will ever entirely remove the table.  I just push it back over the seat and out of the way.  
So far I have kept the original Northstar table top which 18"x36".  The original table top is made of dense press board.  I would say it is as heavy as a brick but that is a gross understatement.  It is as heavy as a couple of bricks.    
I did find at least two similar systems.  Neither appeared to be cheaper, as sturdy, or as adjustable.  The Lagun has 3 adjustments.  The one mentioned above has two adjustments and definitely looks flimsy by comparison.  The Lagun is not cheap, but very sturdy.  It is also designed to be used outside in a marine environment.
Regarding the suppliers:  The Lagun is a Swedish product so perhaps there is a way to order from Sweden.  The price from Marine Teak was really good and the delivery was less than 48 hours from the time I placed my order until delivery.  I suppose I could have checked with Northstar but I have had no issues in the past with overseas orders.  I also found a US-based RV supply company I was not familiar with so I did not want to order from them.