The Suzuki Alto is quite cheap to start with, so discounts won't be massive. However, you should be able to haggle a few hundred pounds off at your local Suzuki dealer. If the salesman protests, mention that you're also keen on the Hyundai i10.
It won't take long to decide which Alto you want because there's just one engine and the only optional extra is metallic paint.
The biggest decision you face is whether you can live without air-conditioning: if you can, stick with the entry-level SZ model; if you can't, it's got to be the mid-spec SZ3.
Every Alto is covered by a three-year 60,000-mile warranty and a 12-year perforation warranty. You also get 24-hour UK and European roadside assistance for three years.