Look for a charger on a site like Amazon. They have a lot of different ones at different prices.
Look for one that also TESTs cells not just charge them. That way you can test a cell after it has been charged to get an idea how well it works as it gets older. These are typically 4 bay chargers that have an LCD display.
They also have different current settings for NiMH cells such as 500ma, 1000ma, 1500ma, 2000ma, etc.
They also sense the condition of the cell and if the resistance is too high they automatically cut back on the current so the cell does not get too hot.
They also show the terminal voltage while charging, the ampere hours, the time, and of course the actual charge current which may vary for each cell.
The discharge test tells you if the cell is getting too old. For example if the cell can hold 2000mAh when new and it is tests as low as 1000mAh then it must be getting old and so wont run a device as long as when new.
A typical charger that does all that is the OPUS BT-C3400 but i am sure there are others in that price category which is probably around $40 USD.