http://www.audiocircuit.com/9110_magnetostatic_circuit/9110IMAI.htm

Some people call these speakers "ribbons" or "Quasi Ribbons". How I define a ribbon you can see elswhere (Ribbons). A magnetostatic work in a way like a ribbon but it has a base of some kind (mylar or kapton) on which the conductor is glued. The coil or conductor is often made of aluminium to keep the moving mass low. Most magnetostatics use a very thin flat conductor, but some still use thin wires glued to the base.

They call it a ribbon, but I think it's a magentostatic. Anyway the specs are very impressive. 110 dB sensitivity and a max peak of 2.500 Watt certainly is far more than we need for normal "in house" listening.

From their site:
"The RBN1801 is an 18" professional ribbon transducer with a peak power handling of 3000W. and is currently the most powerful ribbon driver on the market. It features two patents. Alcons’ RBN transducers are the only pro-ribbon drivers with “Real-90” horizontal dispersion up to 20kHz.  

Alcons' ribbon drivers were developed by Philip de Haan, sr. R&D engineer and 20+ year veteran in ribbon transducer technology. He is initiator of a number of significant patents and can be seen as "father" of today's high-output pro-ribbon technology."

Raidho /(EBEN)
http://www.eben.dk

The end result is a performance that extends from 3.5 KHz to beyond 50 KHz, yet does so with totally convincing speed, resolution and dynamic integrity. The Raidho can be used at lower frequencies than 3.500 Hz, but a gentle roll off from this freqency and down should be taken into consideration.

Sensitivity is stated as 93dB/1W.

 

http://www.magneplanar.com/1-800-474-1646/index.html

The "Maggies" may be the most popular and certainly the most well known magnetostatic. Please note that the top range is a real ribbon!

The Quasi-Ribbon shown is basically the  same driver used for the mid and low frequencies of the Magneplanar speaker with the infusion of a heavier gauge wire replacing the thin aluminum ribbon. Using a .0005" Mylar diaphram and a .001" ribbon this diapole, cabinetless design leaves the sound uncoloured by box resonances. 

The electronic properties of this design requires no transformer between amp and speaker. The flat impedance and power responce are kind to your amplifier.

Brian Cheney of VMPS use these flat magnetostatic drivers in 
the current VMPS line. "custom made for us 
in Canada," but doesn't specify the OEM.  These may be modified 
version of the Monsoon drivers, which are 
themselves licensed from the design of the Emminent Technology push-pull 
planar magnetic dipole drivers. 

Eminent Technology LFT-10 Planar Magnetic Car Speaker

The LFT-10 will offer a new range of flexibility to the installer because of its thin profile and reduced space requirements behind the speaker.

The useable frequency range is from 400Hz to beyond 20Khz. Narrow directivity requires on axis or reflective positioning and assures excellent imaging.

Frequency Response - 400Hz To 20Khz + 3dB
Sensitivity - 86dB @ 1Khz @ 1 meter on axis.
Impedance - 6 ohms purely resistive weight - 4lbs.
size - Length - 7"  Width - 5" Thickness - 1"

http://www.dynasonic.gr

I bought these - see pictures and measurements.

A "ribbon" from Greece? Yes, this country not normally connected with loudspeaker manufacturing has come up with this gem of a magnetostatic called PL-160. 

With the PL-160 Dynasonic takes the technology of planar transducers a step forward. This monopolar planar speaker, is the result of a three year development work, in cooperation with the ministry of technology in Athens Greece. 

The BIC, Binary Interlaced Coil technology, is
based on a proprietary diaphragm (Patend
pending) of two symmetrical coils of aluminium,
printed one into each other on a very thin 12µ high
temperature polyimide film, aligned within the
dense field of a Neodymium magnetic structure.

Sens: 97 dB/1W 1m

Frequency range 1.8 - 40 kHz

HF range

FT7-RP
8 ohm impedance, 3kHz to 45kHz frequency response,
93dB sensitivity at 1W/1m, 0.155kg (0.34 lb) net weight

http://www.bgcorp.com/1Pages/OEMdrivers.html

The Neo8 features a push-pull magnet system that has been designed with the help of Finite Element Analysis software to achieve optimum efficiency/cost performance. The purely resistive impedance of the Neo8 makes an easy load for a power amplifier and greatly facilitates crossover design. The magnet system is completely shielded for safe implementation in multimedia and A/V systems.
Specifications:
* Power Handling: 50 watts RMS/150 watts max
* Nominal Impedance: 4 ohms
* Re: 3.84 ohms
* Frequency range: 500-20,000 Hz
* SPL: 93 dB 2.83V/1m
* Net weight: 1 lb.
* Dimensions: 7-7/8" L x 3-1/2" W x 1/2" D

KaptonÆÊ diaphragm, massive cast aluminum body, direct contact gold plated binding posts, proprietary cooling technique, symmetrical push-pull Neodymium magnet system.

The PRD1000 driver can be used with its standard flat face plate or with specially designed cast aluminum 70° x 40 ° horn.

As far as I can see these may be OEM product sourced from Stage Accompany.