I went through this as well. Did a lot of research and took my time looking for
what I wanted at a price I was willing to pay.
My choice ended up being a Bausch and Lomb Dynazoom monocular laboratory.
They are plentiful as are parts and accessories, the prices are all over the
map. I found mine on Ebay, albeit several years ago for 50 bucks. It was a little
bit rough cosmetically but all the parts were there and they all worked. Things I
watched for were an Abbe condenser with iris, a light or at least the hardware for it,
all stage parts present and a 4 objective turret. (objectives are plentiful, and I wanted
to upgrade to an oil objective sooner or later so I looked for a 4 ob turret with only 3
objectives currently mounted).
Funny thing about microscopes, they are a lot like telescopes! You can hang stuff
on "em till the cows come home! Different eyepieces, darkfield filters, oil objectives,
camera mounts and the list goes on.
Here's mine in its present state and working fine. I have a couple of hundred tops in it
with extra eyepieces, filters and such.
My advice would be do your homework and if your handy don't be scared of an
ugly duckling if it is all there and cheap, could be a swan underneath!