Since the 1N4007 isn't a dual, why do you require a dual varactor? I'd
expect diodes specifically made to be varactors would have less
variation from part to part with respect to capacitance than would some
other random diode.

Have you tried Mouser (as Professor suggests) or DigiKey, or some of
the surplus places like MPJA?

I've heard that 1N4007s commonly make decent PIN diodes. If that's the
case, if they really are made as a PIN structure, I would think they'd
make lousy varactors. Wide-tuning-range varactors are commonly
"hyper-abrupt" junctions, NOT PINs.

Cheers,
Tom