the-ninja-kid wrote:
looking to pay bottom dollar. the cheaper the better.
a free rusty trailer is even better

While I understand your goal here..........
Thats a really bad idea. Start with a trailer thats in RWC condition. Less rust the better. Even if it costs you more money. Rusty/ shitbox trailers can be just as dangerous as rusty shitbox cars.
Oh, and I'll add the old "poor man pays twice" in for good measure
