Daniel,
A sweeper is of no use without a receiver of some type. An explanation of your intended use case would be very helpful.
My first suggestion for building one would be to use a pair of AD4351 square wave generators with switched low pass filters boards such as the QRP-Labs offering:
An alternative choice would be an AD4351 and a AD9834 or similar AD based DDS, Sweep the DDS and step the AD4351 after each DDS sweep.
I'm very interested in your quest and spent a lot of time pondering the subject before realizing I was now an old man and could buy anything I wanted for the simple reason I saved as much money as I could while I was working. I'm looking forward to your replies.
Have Fun!
Reg
