The LM-7 is just a .22 beltfed upper for an AR15 or M16 lower. It'll work on either type lower, so if you want a full auto one, you'll need to first find and buy a registered M16 lower (about $9-10k for a non-Colt conversion, much more for an original factory Colt gun). The LM-7 has not been released for public sale yet, but will be soon (Lakeside Guns was waiting on an approval from BATFE). The pre-release introductory price was $1750, but it may have increased if you didn't get a deposit in on the first batch. I already have a deposit on one and can't wait to get my hands on the thing. From what I've heard from people who have seen and handled it at the SAR show and Knob Creek, its a well designed and made piece. Basically a Browning 1919 action adapted for use with a hammer, and mounted on the AR15/M16 receiver.
What Lakeside was referring to about it not being a firearm or receiver on their website is just the upper. there was some speculation BATFE may define just the upper as a firearm, so to buy just the upper you'd need to fill out a 4473. Additionally, were that the case, if you had the Lakeside upper unit and wanted to cut the barrel down to below 16", you'd need a separate registration for the upper as an SBR - another $200 tax. It had nothing to do with the host lower not being needed to be registered as a machinegun. Fortunately BATFE approved it as a non-firearm, as any other AR15/M16 upper.