A good cleaning of the basic field stripped gun is all thats needed. Lightly lube the rails and you should be good to go.
I wouldnt get all worried about detail stripping and cleaning it. You could get a can of Gun Scrubber and blast the internals until they run clean and then re-oil if its really bugging you.
Top Gun Supply (
www.topgunsupply.com) has pretty much anything you might need for your SIG. They are good people to deal with.
If youre really feeling the need to do something more than a field strip, they also have an armorers CD that is worth more than the $20 you pay for it. It will walk you through a total tear down and reassembly, and is handy to have.
Mostly all you really need are some spare mags and ammo.
You can also get reasonably priced mags at CDNN (
www.cdnninvestments.com/). The used ones are fine too, but Id stick with SIG factory mags myself.