as long as you have to wait and save for funds let me suggest some good servos and motor if i may with out stepping on you toes. not sure if you have any higher C rated but with the right motor on 3 cells the plane will perform just as well as on 4 cells..
any items i do suggest if just some of my thoughts of items i have used with good results and if the items are in stock to.

http://www.hobbyking.com/hobbyking/s...idProduct=4696 have these servos are in my ultra stick 25 and work great.

http://www.hobbyking.com/hobbyking/s...dProduct=18121 i have this motor in a eflight ultra stick 25, with a 12x6 prop on 3 cells it gives over 500 watts and that will give the advance a nice flight fast or slow.

http://www.hobbyking.com/hobbyking/s...dProduct=16231 i used this motor on 4 cell in one of my advances with great results, it was just easer to keep all my packs the same 3 cells is why i went backt