Cost is always a consideration.

Planes:

$100.00 get you a plane that is more like an r/c car that is not attached to the ground. Not much control, only go in circles.

$200.00 get you a plane that has more control, elevator, rudder and throttle. Electric powered and will give you the basic idea of flight.

If either one of those get you hooked you will end up buying the 3rd option anyway.

$315.00 get you a full function radio control aircraft. Hobbico Super Star Select is a great way to start. This option also allows you to expand. The engine and radio are removable and top of the line name brand equipment, OS and Futaba.

Heli:

$1000.00. You need additional items that you will not need with an plane. In addition to that, put aside $100.00 a month for parts. You will crash a heli allot more than you will a plane, in most cases.

Buying used equipment: One rule, either know your product, WELL or know your seller.

In this hobby, you get what you pay for, the more expensive it is, the better it is.

Like the other have stated, the local hobby shop is the best place to start.

Its allot of fun. Good luck.