Hi,
I've been looking for a parkflier but didn't feel like guessing about components. But then I found this

http://www3.towerhobbies.com/cgi-bin...7&I=LXMYS2&P=K

comes with BL motor an speed control, servos. My my question is, based on the included motor and ESC, what lipo battery could I get that would give a decent run time, but be somewhat cheap? How's an 11.1 V 1500 mah be? Or what I be better off with something closer to 2500? Thanks.

Don't forget to pay attention to weight of battery I don't know how much that matters for this plane. There's a website all-battery.com that has some great deals. Tower has a link for a 640mah battery under the accessories of your plane, so I imagine you'd be fine with something in the 1500-2000 range. $50?

's what i figured just wanted to check

With lipo batteries the more capacity the bigger the battery. You would have to find out how big the battery compartment is and go from there.

There is a link to Venom's website at the bottom of the page you linked. The manufacturer recommends this under the 'hop-ups' list on the plane's web page:

http://www.venom-group.com/itemdesc....VEN%2D1575&tp=

You can try this for $15 less, or even get the special, two for $88 so you have a backup:

http://www3.towerhobbies.com/cgi-bin...?&I=LXMDN1&P=8

Or this, for more mah:

http://www3.towerhobbies.com/cgi-bin...?&I=LXMDN3&P=8

Was going to suggest that Venom's site has the same plane for $20 less. If you get it from Tower you can ask the tech's questions about what will work, and if something doesn't work right it will be easier to deal with one store with great customer service. Also will probably save you on shipping.

what is the difference between 15C and 20C lipos?

That is how much power the battery can deliver at one time.
Lets say you have a 1000mah battery and it is rated 15C. That means it can deliver 15X the capacity of the battery or 15X1,000ma or 15 amps the 20C can deliver 20X or 20 amps.
A 2100mah pack at 12C would be 12X2100=25,200ma or 25.2 amps.
Now that is what the battery is capable of not neccesarily what the motor will use.
3D pilots like high C ratings for the kind of flying they do. general sports flying will need less.