For many years, I've recommended a company called Brunel Microscopes to students who have shown an interest in microscopy. The company has many competitively priced models and their after sales service is second to none.
From your description, you've taken an interest in what's called low-power microscopy with total magnification in the range of about x10 tox40.
The DM1 monocular microscope shown on the following link would be very suitable for your needs and is a good budget model.
http://www.brunelmicroscopes.co.uk/dissecting- microscopes.html
If you fancy stereo microscopy, there are other models shown on the same page that are a bit more expensive. Have a look elsewhere on the website too to see if anything else takes your fancy and ask again if you're uncertain about anything.