A suggested approach to finding a rig right for your harmonica playing.
This information is for both chromatic and diatonic harmonica.
Harmony Central user reviews is a very useful site worth visiting anytime you're considering a new piece of gear. Check out what other musician's experience with it are before spending your money.
Before you spend money on gear, spend half an hour just playing harmonica to yourself. Do you like what you hear? Do you enjoy your tone, your playing? If the answer is no, then you need to work on your OWN tone & chops, first. What you play is what comes out louder.
The main points I can make for those of you just starting out is: find a good mic first, they're generally cheaper than amplifiers and portable so you can take your mic with you when you go to test out other gear and get a good idea of what it sounds like with your setup. If you want a clean tone and are looking for something to simply make you louder go for a good vocal mic. A lot of venues have a PA which is ideal for your needs. If you are wanting the classic Chicago blues tone then you'll be best to start hunting around for a tube amplifier. If you want to start cheap there are some nifty inexpensive practise amps on the market which give a great tone and are fine for practising at home.
There is a huge selection of gear out there. I've attempted to cover the most common or highly reputable choices mentioned & recommended among the harmonica community. Little Walter often treated as the God of Chicago Blues Harmonica used all sorts of gear through his time and yet for all of that, his tone is what many blues players seek. If you are searching for that tone the secret is that its only to be found in your chops, not in any one rig.
You could spend years trying out combinations of gear in a variety of settings, it becomes tedious and is always subjective to people's taste and the setting you are playing in. I think the best thing to do is continue to hone your chops, find a practical rig for yourself that delivers a good sound and settle on it unless your situation or needs change. You can spend a lot of time and money on these things and still be no better musician than when you started. Thats time & money that could be put into hours of practise, more harmonicas and a good teacher.
In addition to this site there are some excellent interviews with professional harmonica musicians about their gear courtesy of Richard Hunter.
Good luck in your search for your own "perfect rig".