Hmm, that got me thinking that with that triple DAC, a BeMicro MAX10, and replacing the 75 Ohm terminators on the board with 50 Ohm ones I could have a three channel ARB wavegen using the 8 MB of RAM on the dev board to store up to 2MB of ARB data per channel and still have 2MB for other things like a nice sine lookup table higher than 8 bits for example, sure it would be limited to VGA output levels. Maybe adding some ADCs to it for inputs for AM/FM modulation, maybe with one of the PSoC 5LP prototype boards with a Cortex M3 that cost just $10.
So for under $100 ($42 for the DAC, $30 for the BeMicro Max10, $10 for the PSoC 5LP prototype board) it would be a nice test rig that could get a decent 50 MHz signal gen.
Add some bits and pieces for the interface hooked into the PSoC, add an LCD also controlled by the PSoC and it could be a stand alone unit.