The official 3D trainer of York County Flyers - The Twisted Hobbies (TH) XTRA Slick is a tough as nails 3D trainer. There are about 6 or more of these floating around the club. They are big enough to fly outdoors and small enough to fly at our micro indoor events. If you want to practice any aspect of basic or 3D flight, this is a fantastic and forgiving airframe.
There are only a couple options on this plane to worry about, the majority of it is straight forward. Depending on which direction you go, the whole plane, including batts and receiver, should be in the $120 to $160 range. The RCGroups build/discussion thread is here.
The slick can be found here. There are two primary schemes and several colors to choose from. Most of the guys are using the ARF kits (look for "Twisted Hobbys 32" EPP Xtra Slick ARF"). There are two other options for people that want to save some money by painting their own scheme and/or beveling their own hinges.
Don't forget welders adhesive/glue for assembly. You can order it from TH, or get it from Lowes. You can do the whole plane with a single tube, and it's a necessity to have around for repairs.
The only major decision to make on this airframe is if you want to run 2S or 3S setups. The 2S setup is more than enough power, and really saves a fair amount of weight on this light aircraft. If you plan to fly outside in windy conditions, or just want the extra power, the 3S is the way to go. There are lots of good options for packs in the $4-6 range. In any case, you'll want several packs to keep you in the air. A single pack lasts about 7 - 9 minutes.
Recently, these appear to be the best bang for your buck on batteries. They can also be charged at 5C!
450mAh 2S Lipos (Ship from US): http://www.hobbypartz.com/98p-25c-450-2s1p.html
450mAh 3S Lipos (Ship from US): http://www.hobbypartz.com/98p-25c-450-3s1p.html
1 vs 2 Aileron Servos:
This is a minor decision. TH now makes a control horn set (here) with an offset servo arm for single aileron servo setups that is gaining popularity because of weight savings. If you are going with a 2 aileron configuration, you will have to cut away a little bit of foam to fit both servos in. It's a very minor modification. I believe this is honestly a toss-up.
TH Power Combo:
The Twisted Hobbys "power system combo" (here) is the easiest & fastest way, but not the cheapest, to get everything you need. If you are going to go with the dual aileron servo configuration, you will need to contact Brad at TH to get a custom power combo with 2 aileron servos instead of the standard single servo.
If you don't want to order a combo because you have parts laying around or just want to save a little money, these are the items that you will need:
Motor: 24g 1500kv brushless motor, HobbyKing Motor. Lazer Toyz sells a great motor, the "blue wonder", that you can find here. There's an option for adding an 10A ESC on that page that's worth getting if you're getting the motor from them.
ESC: 10A ESC, HobbyKing ESC. If you get the LazerToyz motor, don't forget to get the ESC combo.
Servos: 5g servos for rudder, elevators and ailerons (when using 2 aileron setup). HobbyKing Servos. If you are using a single aileron servo, you will need a 9g servo (HobbyKing Servo). Don't waste money on "good servos".
Props: A 9 x 4.7 prop will work on both the 2S setup and 3S setup without issues. TH has props, along with HobbyKing.
Prop Saver & Rings: A prop saver will come with the TH combo and the HobbyKing motor options. If you get the blue wonder, you will need to order a 3mm prop saver from the site as well. Prop saver rings (rubber gaskets) can be found on all the sites listed here so far.
Receiver: I would suggest the smallest/lightest receiver that you can get your hands on. If you are on Spektrum/JR DSM/DSM2, I highly recommend using one of these from HobbyKing. They work great, are light, and save a lot of money.