I'm just going to add one more thing -- now that you've posted asking about Interstate as a brand....
Just shoot me if you want to -- but I don't think ANY OF US can wear out a trailer of ANY brand.... I've drug mine all over the place without issue (regular maintenance!).... and I don't think I could live long enough to actually wear it out.
How much towing you going to do?? Seriously -- 4 or 5 thousand miles a year??
I too -- would shop used FIRST.... because these really are just a box on wheels .... but remember they can live at the coast etc and if they're steel - they can and do rust up! Also -- there's no odometer on a trailer... so service items such as wheel bearing and brakes and the AGE of the tires is important!
ALWAYS check the dates on the tires.... NO MORE THAN 6 years old -- so if they're already 5 years old - you're going to be replacing a set shortly.
Brakes on this size trailer are almost always electric... if the trailer doesn't get used much - or has been sitting - they can be rusted up and not working well.
WHEEL BEARINGS are a critical item! Overlook them and you can have a big trailer fire and lose everything... I almost lost my load when pulling my brother in laws POS trailer to AriDzona. Their trailer was a POS pile of junk but my '32 Ford isn't. It was real real close to bursting into flames. Lesson learned there.
So here's what I'm trying to tell ya --- IF you buy used --- plan to spend $500 plus on it IMMEDIATELY at a dealer getting it serviced and road worthy. More if you have to replace tires.
I look at those pics and think wow that it great then I see the car in the nose on the lift is completely ahead of the axles. I have no idea what he is towing it with but that is alot of tongue weight.