If you are talking about the BFL Single that does 25gh/s, it's not even confirmed they will ship let alone making plans to buy. PPcoin can be mined with power or without. Yep, you don't need any mining power to mine PPcoins so long as you actually have some amount and let them age more than 31-32 days.
I.e. I just can buy PPCoins at the exchange and just ... hold them. Right?
Should I be online all that time?
As I understand from PPCoin FAQ I will get 1% reward per year.
It's not so much...
I think with any cryptocurrency you are mining you have to look at it from two perspectives:
1. Are you mining it to make a quick buck because you think PPC has an edge over other cryptocurrencies or;
2. Are you mining it because you agree with it's ethos and want to work with it and help it achieve wider adoption?
Both will provide you 'value' but what are your personal needs and objectives?
Personally I want to try out a number of different economic models and PPC is sufficiently differentiated that I've invested some of my time and money into it. Either way the exercise will have been of value to me.