If you take another look at the WhippedDog website, Larry's actually got a "Rich Man's Strop" now. It's not a question of new vs. used--take a look at both that and the Poor Man's Strop Kit and you'll see the differences.

As to your second question: well, it's a fact that you're going to nick your leather strop. We've all done it; some have cut their strops so badly that they haven't been able to repair them. Larry also offers a two-leather strop deal which you can also bundle with the pasted balsa from the Poor Man's kit. I think having a spare on hand would be a good idea. And while you're learning to shave and strop a razor, there's also the possibility of rolling the edge of the blade or otherwise damaging it. This can be an expensive undertaking, and I've read several posts (a very few, admittedly) on the forums here from guys who went all-out and spent a lot of money and then decided it wasn't for them. I guess if it were me in your place, and knowing what I know now, I'd go with the WhippedDog deal, even if cost weren't an issue. Those Dovos will still be there once you've gotten the hang of this and decided you're sticking with it. Hope this helps, and good luck!