if its not a special car with a big battery or load rating etc, just any old $29.95 supercheap charger will work just fine
the only reason I spent more than $30 on my car is because my charger has a 'jump-start' feature in case you need to jump a totally dead battery
just make sure its 'intelligent' - so it knows to turn off once it's fully charged
there really is nothing to them for your average car battery
i bought one recently from jaycar, but it wasn't just car batteries i wanted to charge - it was also for AGM SLA (UPS) batteries. The more you spend, the higher the output. Even then my $80 one takes a couple of days to fully charge 80ah batteries from flat!
If you leave your car for long periods of time like I do, use a charger that has a trickle function and leave it plugged in all the time.
Once the battery is fully charged, the charger will change to trickle mode, which stops the battery from discharging.
BTW, from the above link, it's a 4 amp charger, that is no where near enough to jump start a car. I'm not sure how many amps you need, but I would guess in the range of 300-600 amps (look at how thick jumper cables are compared to your battery charger cables)