One of the possible rewards of the Bug Collection quest is a stalking probe (normally a tinkering item). Someone named Gwideon has been selling these in the EC tunnel for 100p each. He's sold 12 of these in the last 30 days.
Other possible quest rewards:
Bracelet of Beetlekind (50-100p)
Potion of Poison Warding (400-500p)
Silver Bracelet (400-5000p, average 600)
Spider Venom (no auction records - player crafted with Poison Making skill and probably not worth much)
Giant Wasp Wings
Re: Giant Wasp Wings
Hmmm, we may need to talk to Blixkin.