If I may insert a thought or two...
We started with the D70s camera.
And the 70-300 ED, not the G model.
(VR version could also be considered but is
more money...)
This lens really launched us into birding...
and, with a tripod I came to enjoy closeup
with this lens (also with the 5t & 6t closeup
diopters).
I mention this as your friends could find a
nice used camera, or even two different cameras,
and lenses, for a very inexpensive setup.
As beginners our "sharpness" and "bokeh" and...
expectations differed greatly from what they are today.
The 28-105 is a very nice lens as well.
Two cameras and lenses can be had for probably under
$800 or $900...(so they don't have to change lenses).
This might also give everyone the opportunity to photograph
something on the trip. And this is a fairly lightweight option
which can produce very nice pictures...
Just another thought to consider regarding beginners
expectations, and enjoyment with simple tools.
_________________________
Cheryle