Do yourself a big favor...save your lunch-money and buy a good-quality metal detector! I started out with a Garrett sea Hunter MK II for $600 and had pretty good success with it. But being a PI machine, I was wasting too much time and air digging junk targets.
I got myself a Minelab Excalibur II for around $1400 and it paid for itself with my first find, a 2,500 Euro 18 K, diamond ring!
Most of my friends started with low-quality detectors and almost immediately experienced "buyers-remorse".
You'll find that the Vibra-Tectors are virtually useless as a primary detector, but in Vibra-Tector's defense, they make an EXCELLENT 2-inch pinpointer that is good to 100 meters. This is my go-to pinpointer for underwater metal detecting and it is the best underwater pinpointer that I have!