Woah. $90 for a 10-cell pack of GP3300s? I think cell cost is around $6.25 each for those where I shop. You could get two CP2400 NiCd packs for the same money, about $90.
Great Planes C50 ESC is only about $50, IIRC.
...and Tower's out of Endoplasmas as of this morning. If Tower's out, everyone's out, so don't bother asking where else you can get one
The Duraplane 20's wing loading will be awfully high. If you want slow, stable, and easy-handling, get a Tower Trainer 40 ARF instead. With the same power system, it comes out lighter than glow. By no means is it a stump-puller, but it does okay for itself.