You can get a duracell brand trickle charger at Target for $20, you can hook it up overnight to charge and it does a good job. I used it on my SLA battery on my motorized bicycle and its great.
There are 3 connectors that come with it, one to perm hook to a battery, one with traditional charging clamps and... one other than I can't remember what it does. I have the permanent one hooked to my battery. I go out ride and then when done plug it in. Simple and easy.