How hard would this be?

An excellent source of antenna information is W4RNL's web page at
html://www.cebik.com/radio.html

Down in the VHF antenna section you will find his articles on quads and
the OWA yagi designs. Both of these are excellent and are easy to build.
I've built the 2- through 4-element quads for various bands and they've
worked great with no adjustments or tuning required. (And I can
compare several antennas against each other, so this isn't just a "seems
fine" sort of recommendation.) The OWA yagis have a very clean pattern
and a direct 50 ohm feed impedance, though I prefer the "Cheap Yagis"
referenced above for homebrew wire designs because the driven element
is mechanically more stable. I think W4RNL has a downloadable
spreadsheet for quads and 3-element yagis - look for his Antenna
Design spreadsheets in the Antenna Modelling section. These require
just the entry of the desired frequency and element diameter to generate
a number of antenna designs.

Also check his Antenna Options series of articles down near the bottom.
This will give you some idea of choosing antennas and how you can
build your own. I use PVC pipe and copper wire and I think I estimated
that it cost about $1 per element to build a quad, but that was before
the cost of copper went up. But it still isn't very expensive.

And it isn't difficult to build antennas for 440 that will run rings around
any CB antenna in terms of true gain - for example, he analyzes some
antennas with 20+ dB of gain that are over 13 wavelengths long. That
would be over 400 feet long if built for CB! But on 440 MHz it is less
than 30 feet - much more practical to build. However, I suggest you
start with something more simple - perhaps a 3-element yagi or
2-element quad.