Yazuka,
There is nothing wrong with starting out on a 50, 60, or 90 for that matter. It's all about economics. If you can afford to purchase, fuel, AND maintain a 90 then by all means go ahead. But, what's more important is the radio equipment. Spend as much here as you can. Remember with good quality servos, gyro, and transmitter you can make ANY heli fly great. But, NOT the other way around.

I advise most beginners to think long term when it comes to RC helis. Buying a larger size heli is actually wiser because that is what most pilots evolve into anyhow. So, why take the depreciation hits on a 30 if you don't have to?

As far as .50s go I recommend the Century Falcon 50 SE V2 or the Raven 50 CCPM. My avatar is a shot of my Falcon SE V2. It is powered with an OS .50 SX-H and flies absolutely awesome. I have since converted it to a Raven 50 CCPM. Basically, the Raven is a CCPM version of the Falcon.

These two machines are equipped like a 60. They are built for the demands of 3D and come with TONS or upgrades IN THE KIT! You get:
4mm Flybar
10mm mainshaft
6mm spindle
Carbon Fiber torque tube drive
Triple bearing tail rotor grips
CNC Metal headblock
Low Profile Tuf Strut landing gear
600mm Hurricane fiberglass blades
....and more.

I have owned the Sceadu 50, and Raptor 50 and as far as smooth, stable, dependable flight these two machines have them beat!! And, they are made here in the USA.

Check them out at www.CenturyHeli.com