I have 2 trailers I use DAILY. I have one hooked to the other hooked to my bike. I pull 3-6 kids 1 mile to school daily. I got them both on Craigslist for less than $30 total. They are like bikes in that used is just fine, with tires and wheel bearings being pretty much the only serviceable items. Prove your mustachianism to your mom by selecting a used one from the Internet!
Especially a good idea since its your first and you're not even sure what/if you'll use it for