elijahenry10,
Why do you need a dredge? Do you know there is gold where you are going, I mean without a doubt and how much? (I do not want to know your location/(s)). IF you know there is gold there what type, flakes, flour, nuggets, wedding bands (don't laugh-some fellas did very well dredging down river from "I just got divorced bridges" in Nevada where folks used to throw their rings away)? How Deep? What kind of soil, sand, mud, rocks? How much water flow in Cubic Feet Per Second ( google USGS Real Time Water Flow Data for your state and see if your water source is listed then see what kind of flows it has at what time of year )?
What SAFETY PLANS do you have/need in order not to die while dredging? Do you swim well? Do you get cold easily? Do you have someone you can trust to be topside to sort out problems up there while you are diving or do you need to dive??
IF you think there is gold there then you need to find out first, buy a gold pan, use a classifier (like an old vegetable collendar for getting the water off of lettuce) to pre-sort the dirt you want to test for gold as that saves a LOT of time, panning is slow and will kill your back from leaning over the water supply. Do you know how to 'read a river'? Google "how to read a river" and see what comes up. Do you know where to look for gold? (how to read a river is a big part of this) Some simple techniques coupled with some simple tools (classifier, small shovel, gold pan, sample bottle, magnifying glass) are all one needs to get started while a dredge is what one uses ONCE the gold is known to be in a certain spot/location along a river and that the real gold is on the bottom (and that is where it usually is even if one finds some good pickers up on the ground around the water).
There is a lot of prospecting information on the internet, if you haven't already, look it up, read it, its free except for your time but you are actually saving yourself a lot of time by becoming knowledgeable about the hobby you are getting into before you step out your front door or before you spend your first $25 on a panning kit say from Garret. I've been playing with prospecting for a lot of years, being in California within 175 miles of NorCal Gold Rush country I've almost always found some along the banks of streams and rivers but I did not have anyone to guide me like the folks on this site are doing so I waisted a lot of time and some money (bought a 2" protable Keene dredge in August of 1992, used it three times and its been sitting since then but the motor and pump will soon be used on the high banker Im putting together, no it is not for sale) I've found more gold since getting a Gold metal detector and a sluicebox but even then I waisted time and money as I did not really know how to use them. Educate yourself before you plunk your Hard Earned Money down on something that will end up at the back end of a barn........Best of Luck 63bkpkr