I'd suggest taking a look at the HiTec chargers. They have AC/DC connections, meaning that you can plug them into the wall, or hook them up to a car battery or other DC system. This is a bonus for several flying fields like my field; we have a charging station that utilizes a solar panel and a couple of car batteries hooked up to it, which is a DC system. All I have to do is connect up my alligator clip connector and plug it into the back where the DC connection is, and it recognizes and turns on - no switches or anything.
With the HiTecs, I can charge Li-Po, LiHV, NiCad, NiMh, Pb, LiFe...Pretty much any type of battery needed for the hobby. I can also charge from 1S up to 6S batteries. Anything more than that, and, well, perhaps you should be doing it with a certain level of electrical engineering understanding, because at that point, you're getting into what I consider dangerous current territories.
As for cost, well, THAT depends on model, which breaks down to which features you really want/need.
I bought the RDX1 - this thing is AWESOME. I think I paid $60 for it when I bought it, and I can charge everything mentioned. It's also got a USB charger on it, which is great; I can charge my cell phone while at the field if I need to, just plug it in and go. Also, the charger's SMALL. I can fit it into an Ammo box, put it on my desk and have it take up very little real estate; I have my portable home phone base station charger that is actually bigger than this thing.
For those who feel they need to buy something made in America, they're manufactured in Poway, CA - that's another reason I really like them. They're only about 1/2 an hour away from where I live, and they have a lifetime warranty on their chargers. Something happens to it, they'll replace it.
The only downsides to this particular charger that I've found are that it'll only do 1 battery at a time (balance charging, which is how I prefer to charge all but my 1S batteries, since you can't balance charge those), and that, when I bought the RDX1, it didn't come with connectors for DC connections - I had to wire my own. THAT issue, however, was remedied in the RDX1 Pro, where they give you connectors for DC in the box, a connector for XT60 batteries, and one for Deans T-style connector.
So, which one am I recommending for you? HiTec RDX1 Pro. $70 through AMain or Tower Hobbies, or Amazon.com. It's $10 more than the RDX1, but it's got more power to charge faster, an already built DC power cable, and you get a Deans and an XT60 connector in addition to the AC power cord, AND the instruction manual and onscreen menus are pretty easy to understand.

This was my first charger in probably 25+ years, and having then only done a quick charge here or there of old Tamiya batteries for cars, this was a HUGE step up - and pretty self-explanatory.
Others will probably recommend their favorites; I'm kinda curious to see what else is recommended! But, this is mine, for the aforementioned reasons.
