I agree with David, nothing beats alu but it does get expensive. I do find pl2 Kirschbaum to be close but not quite as good as alu but it's a good bit cheaper.
I tried out PL1 this week and it's not nearly as good as alu. I've got some K'baum spiky shark which I'm hearing good things about. It's supposed to have extra bite and feel similar in construction to PL2. I'm playing with it first thing in the am and I'll let you know how it goes.
I've spent the last year of my life trying to find a sub for alu and I can't. CF is nice but it doesn't have the "alu pop" but CF does hold tension much much better.
Regarding the spiky shark, Tennis warehouse has a promo on it right now where you get three packs for $24 which is good for a first rate poly.
Give the PL2 a shot, I 'll be surprised if you don't like it. Also, have you tried BBO, you can get a mini reel with 3 sets for $30 and that's about as close to alu as you can get. It's a bit more heavy handed than alu but it's a great string in the Pro.
BTW, I use the Prestige Pro as well, great stick!!