Depending on your future plans go for the biggest trailor you can find in decent shape as you will find more uses for it than orginally planned

I recently picked up a 7x18ft long trailor for 900 decent tires and all and in the past month hauled more junk I have been putting off getting ride of that I could have ever imagined my orginal use was to take my 1980 to and from places

good luck with your search check tire condition as well as type as trailor tires weather better than car or truck types do (Dry rot) also if you look at used check wiring condition as this can be a big pain as well as jack it up and check for play in the wheel bearings as this can add the cost as well

have a good search
Jim Ed