I am glad I went with a self designed 3D Printer.My design continues to evolve as I continue to use it.I began with a very simple design that used a floating Y rail, with two rails (the entire rail system for the Y axes moving up and down along the Z axis). Now I have the X axis rails suspended above the bed, a single Y rail, and the print bed is lowered away from the extruder head instead of the extruder head lifting. It is much more stable with the new configuration, and is easier to expand in the future for larger print volumes.Then there is the controller. I began by using the GPIO pins on a Raspberry Pi Model B, hooked up to three ULN2803's, with a few voltage regulators and a 12 volt power supply. I found that to be a problem so I moved to a Arduino, that had its own set of issues. So I dug up one of my old Parallax Propeller P8X32A boards, and I am now using the Propeller for the controller, still using ULN2803's for the current sinks, and the extra voltage regulators, along with a 12V power supply for the motors and heating element.So designing a 3D printer from scratch has taught me enough to know how to do it correctly. I now have a very stable, reliable 3D printer (still adjusting for scale [only 4 hours since the last revision]).And if I had began with the design I ended up using I would have saved $40, making the total cost around $140. If it were a commercial product with a production cost of $150, and about half an hour of labor to construct copies (repetition reduces time to do well), that would be $140 + $10 for labor, + 20% profit equals $180 for a fair market price. And we all know that buying in bulk reduces the price of parts, so if some one did mass produce this design (at least 10 units per run), it would cost closer to $150 retail, for a fair market price.I would like it if all those that do produce 3D printers to sale to remember what it actually costs. And if you are thinking about getting into the market, I would recommend that you do like I have so far and design your own, write all the firmware, test, modify, test and modify some more. Then produce your first run, keeping the profit labeled at $10 labor per unit, plus the cost of parts materials, and utilities used for the application, plus a 20% market up.I will never get into selling them, as I do not have the greed to want to make more money, nor do I have the resources to support a customer base.