The cobra and Twister lathes are great simple lathes. If the support blocks have not been knocked out of alignment they are good lathes.
The Fantom is a single piece support. It will cut straight for YEARS! Yes the lathe is $400 but add up what you get. You get a sealed carrying case, 4 cell battery, DIAMOND cutting bit, slave motor and cutting fluid. Best of all it is setup and ready for you to cut out of the box. All you need to do is solder up the supplied switch between the slave motor and the battery. I installed a deans connector between the battery and the swtich for easy storage and charging of the 4 cell battery.) Once you add these accessories to any other quality lathe you can run up to close to $400 on any one of those lates. Also the case Fantom gives you is really nice to protect your investment. If you are just looking at lathes I do think the single piece machining for the arm support will ensure the lathe stays true. I have seen a lot of 3 piece (base and two vertical arm supports) get knocked out of plane which will result in a cone shaped comm. The Fantom has been worth every penny.