There are several factors to deciding what banjo is right for you, here are three things to consider:

1. What style are you interested in playing?
2. How much money do you want to spend, and how serious are you about the banjo?
3. How big or strong are you?

1. First off you will need to decide what style you want to play. there are two main styles, Bluegrass banjos and open back banjos. Bluegrass banjos are by far the most popular, and are used for a wide genre, from bluegrass to rock and roll.
Open back, or old-time banjos are used mostly for clawhammer or frailing, playing old-time folk songs.

* Bluegrass banjos have a “resonator” on the back which drives the sound forward making it louder than the open back type. The higher end Bluegrass banjo will also have a tone ring, making a much richer sound(and also a much heavier banjo) and even louder

* Open back banjos are mostly used for playing old-time, or folk music. They don’t tend to be as loud because the sound is lost in the belly of the player rather than resonated forward as on the bluegrass banjo. The sound tends to be more “plunky”, less bright sounding than the bluegrass banjo, traditionally clawhammer players don’t use finger picks, contributing to the plunky sound

2. You can spend anywhere from $100 for a cheap used beginner banjo, to several thousand for a very nice quality instrument. If you aren’t sure if you will be playing for long a cheap beginner banjo can be quite playable, and is just fine to learn on, however if you are sure that you will be playing for years to come it would be advisable to get something a little nicer if you can afford it. It is worth looking for used instruments sometimes you can get a better instrument for a lot less money.

3. The reason I bring this up is that a nice banjo with a tone ring may weigh up to 15lbs, and that can get wearing after a while. A cheaper banjo without a tone ring may only be 5lbs. If you need something lighter there are great sounding instruments in the lighter category

A few things to look at when considering a banjo

Tuners – Having good tuners is key to keeping your banjo in tune. There are geared tuners and friction tuners. typically you will find on a cheaper banjo the 5th string tuner may be a friction tuner, which can be prone to slippage, and takes much more practice to get in tune. geared tuners are typically geared to a 4:1 to 8:1 ratio, making it easy to fine tune the instrument. Friction tuners have a 1:1 ratio making one turn of the peg change the tone drastically, making it much more difficult to control. All tuners on banjos I have seen have tension screws on them which allow you to tighten them so that there isn’t slippage, however old friction tuners may be worn out and unable to tighten enough to hold(very frustrating). If you have a banjo with a friction tuner or it’s just worn out, they are not all that expensive to have changed out(or you can do it your self if you are the handyman type).

The Action – this refers to how far off the frets the strings are. It is important to have the action set low, but at the same time the strings shouldn’t buzz on the frets while playing. If set too low the string may not buzz when played open but could buzz when played fretted. Since the banjo is pretty much totally bolted together, as opposed to the fiddle or guitar which are glued together, the action can be adjusted with some technical skill.

It can be a little difficult to analyze the quality if you don’t have experience with such things, but basically a poorly constructed banjo will never sound as good and will be harder to keep in tune than one with solid construction. Buzzes and plunky sounds can be caused by many things such as bad strings, loose bolts or screws, loose head skin(the drum looking part), or the bridge in the wrong place. Fixing any of these problems will help the overall  sound of the banjo.

Well I hope this answers any questions you may have, feel free to ask any banjo/music related questions you may have.