Not at all! (harder to brew amber)
If the kits come with a first set of ingredients you can customize an amber, I'd think. If not, you can buy an amber ingredient kit as well and brew it as your second brew. Or brew the amber as your first brew.
Also despite fancy form order web page look, there's human beings behind the front. If you write an email that you'd like a starter kit but would prefer the amber ingredient kit rather than the ingredient kit that's bundled with the equipment, I'm *sure* they'll be willing to work something out.
Meanwhile... Northern Brewer has
9 Amber Ingredient Kits (I'm assuming you want to start with extract although you, of course, don't have to). But you are right. The choice for the starter kit only comes with 3 choices of ingredient kits. I actually imagine that this is simply to avoid intimidating customers more than anything else. Try sending them an email and see what the say. (Or you can order the amber ale kit at the same time and make their default kit your second brew.)
The Midwest Supplies Equipment kits don't come with your first ingredient kit (factor that into the cost comparison) so you can order
their amber ale ingredient kits separately. Or you can order anyone else's amber kit. (My LHBS makes
a good one ... jes' pluggin' .... Actually, since my LHBS has been so good to me I guess I should point out they maybe have
a decent equipment starter kit too. Although it's probably not the cheapest deal you can find. Especially with shipping.)