So... what makes a "good" charger?
A good charger (for lipos) has several cutoffs. First, is the usual voltage, and current cutoffs. Second is a "this battery is bad" and won't charge cutoff. Third is a "this battery has taken to long, and something is wrong" cutoff.
A good charger will have programs for balancing cells, setting storage charge, discharging packs, and good programs for handling other cell chemistries.
A good charger will "save itself" if something goes wrong. For instance my B6 has temperature and voltage cutoffs. If it gets to hot, it shuts down. If the input voltage sags, it shuts down.
The B6 series chargers have all of the above. But why is a B6 charger $30-50 and other chargers $4, and other chargers $200?
It comes down to features, and capacity. Cheaper chargers than the B6 tend to not have adjustable current, and typically do not have timed cutoffs. Some do not even have undervoltage cutoffs. They get cheaper, by removing features.
B6 chargers have "all the features". So what makes more expensive chargers cost more? Well the B6 chargers have pretty low current limits. Their maximum discharge is 1amp, their maximum charge is 5 amps. When you're charging a 16ah battery, 5amps isn't a lot.
Also, some B6 chargers have a built in power supply, that too brings up the cost.
To cover your question directly, a $15 charger is not going to have much adjust-ability (if any..), and it won't have many of the battery, and user protection features. A $200 battery charger is likely to have more than one charging channel, and the ability to charge much larger, and higher cell count batteries at a reasonable speed.