Hello Sgt, thanks for your service, and a hearty welcome to treasure net.
I recommend building your own sluice, for several reasons:
You can build one much cheaper then any of the 'name brand' sluices. A fraction of the cost of a 120 dollar sluice.
It might not perform as good as one you would buy on your initial design, but as you learn you can make changes or create a new sluice from what you have learned that will perform just as good as a name brand version.
Making one out of wood is painless, all you need are very simple tools, some wood of course, a tape measure, some kind of saw, some kind of waterproof sealant to seal the seams, and some kind of waterproofing for the wood. Carpeting, an inspection rubber mat to show if your catching gold, and several different types of riffles are all things you can add (or subtract) as you want. Also a flared opening to bring in more water is another option to build or not. Plus you can build the exact size sluice that will fit into your vehicle.
If you make one out of aluminum, the price will be more costly to make then wood, but you can expect years of reliable service out of the aluminum, whereas wood might become cracked and chipped with age (and transporting the sluice to the spot) not to mention expansion and possible warping if the wood is not waterproofed correct.
If you want a lightweight sluice, an alternative to aluminum is ABS plastic, which you can buy from scrap lots on Ebay for pretty cheap, then put it together with ABS plastic glue. You can also use that glue if the sluice breaks or needs repairing.
There are several how to make a sluice sites and threads that you can consult for advice and directions, or you can just start a post here if you have specific questions.
There are also several alternative things you can use to keep the cost down, vs using the expensive to buy sluice materials (such as low cost alternatives for miners moss).
If you just want to buy one, then everyone has their own opinion on what works and what is best. Every sluice has both drawbacks and benefits. A popular thing nowadays seems to be the drop riffle design, which I think has a lot of potential mostly due to the fact that its so easy to clean up. My current custom sluice I made takes about 5-10 minutes to clean up and then reassemble, which feels too long when I am out shoveling gravel and want to maximize my time spent on recovery and minimize downtime.