You can probably rig up some method for using regular photographic
closeup lenses on just about any cheap camera, this being a
metalworking group and all. Just don't cheap-out on the closeup
lenses.

I've got a Canon G3, myself. The G-series has a macro mode that gets
down to 2 in, plus a manual focussing mode. An f2.0 lens makes it a
little faster than most of the competition. Has an external flash shoe
and you can get accessory bayonet snoots for using regular screw-in
filters and close-up lenses. I've been happy with it. Was about $200
or so as a factory refurb a couple of years back. You might be able to
find a good deal on the net looking for refurbs or the usual places for
used gear. The latest G6 has exactly the same glass as my G3, just
more features and a higher pixel-count sensor. At the time I got my
G3, Canon's G series had the most bang for my buck for the features I
was looking for.

One thing I know that Canon does have is remote control via USB cable
through the PC, not sure if anyone else has that. You can use your
computer monitor for composing and focussing that way instead of that
dinky LCD panel. Might make macro shooting a little easier. That
program is on the web site. They also have an SDK available for making
up camera interface software, if you want to customize the PC side.

Stan