I was at Lowes the other day. They have trailers. I stopped to see the price and how big a 7x12 is because I was thinking on getting a 7x14 in the spring.
They cost $1,799 and were very poor quality. Tractor Supply has trailers in that same price range though I have not seen on in person so I can't say about the quality.
As to dual axle the problems people post about is that the tires wear out faster.
Yes a dual axle trailer with two 3,500 lb axles will be rated to about 7,000 lbs.
Yes I know they have higher rated axles available.
Thing is a 7x12 single axle trailer may be your best bet. Lighter trailer saves fuel, single axle tires last longer. Then if you can keep your truck weight and trailer rating to stay 10,000 lbs or less you won't have to have a DOT number, drive pass the truck safety checks miss out on getting fines.
If your truck weighs 5,500 lbs you can get a trailer that weights 1,000lb and rated to carry 3,500 lb you get a combined gross loaded weight rated up to 4,500 lbs and be Dot free. Of course these numbers are used as an example. You will have to shop and research to make sure the numbers work out for you.
Many LCO's I see can get buy with a single axle trailer rated for 3,500lb.
The thing is to remember the difference between need and want. This will always keep you from spending more money then you have to. I see too many crew cab dual rw 3/4 & 1 ton diesel pickups that never leave the pavement or carry anything but their wives shopping bags from the mall.