To locate the Dragonball, you really need a device. A radar of some sort. You have two options. To approach Frieza's henchmen for a Scouter which need to be customized to detect dragonball or Bulma for a Dragonball Radar which she designed for herself.
Bulma would be a safer choice.
Bulma Dragonball radar was introduced in the early stage of the Dragonball series. It goes to show Bulma was not only a spoiled brat but a brainy gal as well. It is quite a trustworthy device. However it will not detect any Dragonball should the Dragonball was swallowed by some living organism.
If I remember correctly, Goku also used it during the beginning of Dragonball Z to locate his son Gohan from the hands of his wicked brother, Radditz. This is possible as the 4 stars Dragonball was with Gohan.
As for the toys, the Dragonball radar design was made into a wide range of gadget. Here are some of it.
A MP3 player from Banpresto (128MB space only).
Also from Banpresto, a minic Dragon ball radar toy. If the Dragon Ball is near the radar, just press the radar button and the radar will start beeping. The display on the radar is fixed tho.
Do you prefer a dragonball radar or a scouter?
Updates: I managed to get a Dragonball Radar candy toy!