Here's an actual possibility, a Audiobahn AW1505X for $240. With the 2ohm voice coils wired in parallel, it should be just right for the MTX.
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http://store6.yimg.com/I/competitiondirect_1657_54467956[/img]
Massive 180 oz. Double Stacked Strontium Magnets | Power Handling: 1000 watts R.M.S. | Frequency Response: 20Hz – 700Hz | Efficiency: 94.8 dB | Bolt-Tight Motor Structure | PHAT 2 Inch Foam Surround | Laminated Glass Fiber Composite/Pulp Cone | 3 Inch 4-Layer ASV Voice Coil | Dual 2 Ohm | 1 Ohm or 4 Ohm Operation | Mounting Dimensions: Depth; 7 5/8 Inch Hole; 14 Inch Diameter; 15 1/2 Inch
