Being an electric guy let me add here.

What makes many electrics suitable for the "park" is their smaller size, lighter weight and their ability to fly fairly slow. To do that you need to keep them light and standard servos are not really going to meet the need, but might work in some of them. However microservos are not that expensive.

Here is the key question. How much space do you think you have? Is it 100 square meters or is it 1000 square meters. That will tell you something about the speed of the plane you want to fly.

A ZAGI fix might fly comfortably in a 100 square meters but some of the ZAGIs do 70 MPH out of the box.

A slow stick or a tiger moth can be flown indoors or in a 30X30 meter space space. Theycan fly so slowly you can trot next to them. Get a 4 mph wind and you can hover them motionless, even walk up and pet the plane in flight. But you would need micro servos and a micro receiver along with the appropriately light NIMH or LIPoly batteries.

You can pick up a tiger moth or a slow stick 3 channel plane for about $40 US with the motor included. Add a GWS a flight pack that includes servos, ESC, receiver and flight battery for $80-110 US. The e-starter is a 4 channel parky that flys pretty slow. The somewhat larger Tiger Moth 400 with ailerons is about $70 US and can handle mini sized equipment. You might be able to use standard servos and a standard receiver but the extra weight is going to drag the plane down.

Final message is that electric parkflyers can be VERY fast and requrie a lot of space. If you don't have that space, go for a slow flyer.