I bought the cheapest version of the JDS6600, which goes from almost DC to 15MHz for EUR 60.
It has an USB connector on the back which I have never used.
It's not the best function generator ever, with it's R-2R network the output is quite noisy at low levels, but it delivers an amazing bang for the buck. For low levels you could use an attenuator on the output.
The wallwart delivered with this function generator is crap though, but there is plenty of room inside for a little transformer with low capacitance to Mains and a LM7805.
What does "Scalar" mean in the context of a signal generator?
You may be able to do something usefull with a chip like the MCP4922.
This is a resistor string ladder DAC which can be used in "multiplier mode". This means that it is not referencing from a DC voltage source, but from an externally applied signal and the output is divided by the resistor ladder.
MCP4922 only has a 450kHz bandwidth though, but it should not be difficult to find chips with a higher bandwidht.