Well, not sure exactly what you mean. There are powerheads with built in oscillators (the powerhead nozzle moves back and forth), there are water pressure powered devices that take one outlet and split it into two, then alternate which outlet gets flow, and there are electronic devices that turn pumps on and off at specified intervals.
Cheapest is probably the first (I have one from petco that cost me about $30). Second is really only viable if you have a sump plumbed so you actually have a strong return line.
The electronic device gives you the most freedom and flexibility, since it can control multiple pumps and you can set intervals.
But, it all comes down to preference and budget. Many people get along fine without any wave maker device.
Someone stop me! Please! But... not just yet...
55 Gal Tropical FW
55 Gal Mixed Reef