Since your learning anything used would be a good choice. Your gonna beat the shit out of it and why buy new when your gonna trash it?
If your set on getting something new, anything with a full Twin tip and full traditional camber would be a good start.
Here's set up that might interest you that on the Steepandcheap.com right now.
Dynastar 6 sense superpipe
I have never even ridden a Dynastar twin tip but reading the specs of this ski (skinnier ski, Half cap/ Half sandwich construct) it would make a solid learner parks ski for you. At $231 for brand new twin ski thats not bad at all.
Also check this binding out thats also on S&C. 4frnt Deadbolt 13. Very underrated park binding. Just as good as any other 12-13 din on the market.
If you wanted somthing a little wider you could go this ski Dynastar 6 sense Disortor. It is full Cap though.
The main reason I recommended these skis is they are made my a reliable ski company and cause I just saw them on the new S&C section of thier site.
Anyone who has actually ridden these ski chime in please.
Hope this helps OP.