Hey man,
I'm a fairly new Lizardmen player myself. The battalion box was a great start for me. I've bought another box of Skinks, and Saurus to give me a well rounded 2000-pt force.
The Steg, Slann, and sallies are all solid. I did do my own conversions for Sallies, though, I find the GW models to be a touch fugly.
The only thing I'll warn you of is the sheer amount of Flak I've caught at my local gamestore for Lizardmen.
Slann are incredibly hard for people to deal with with their item/discipline combos. Salamanders are the same way, people have no real way to compete with the super-templates they lash out.
Just... keep it in mind. Fielding 3 Sallies, a Slann, and a Steg will probably earn you quite abit of ire. For friendly games, that is.