+1Sage advice I'm sure ... but you have to be able to build it, sell it, ship it - at a price that your customer will pay and to enough of those customers to recoup your ramp up / development costs to justify the investment. It's pretty simple - identifying the broad based need is the tough part. Clearly the guys at Avatar are smart enough to have done that and have come to the conclusion that what you're asking for and will purchase is a $600 cabinet that will cost them $601 to deliver...
My contention is that it is as much the limited market for 610's and tranmsport costs as anything ... You can only pass shipping costs along IF your customer is willing to incur them...
The market is always there for any cheaper interation of a product. Nailing down the exact pricepoint can be a bit tricky.