just keep looking on craigslist for old hobie 16s and sometimes the value of the trailer exceeds that of the boat and trailer so that it is worht it.
also, just post a wanted ad on craigslist directly and youll be suprised what you can find.
lastly, use the yellowpages and call up local trailer repair/ mechanics/ maintenance places/ as well as junk yards. You'd be suprised whats lying around or for sale. im sure youll find something if you just look around hard enough. depends how hard youre willing to look/ how much time youre willing to invest.
i lucked out on my best trailer, and got it with my beautiful H14T(and soooo many extras) for only $100. Much better than the $440 i paid for a rusted old trailer, an H14, and parts of a H16. Before that was $500 for a great condition H16, but with a horrible trailer.
so its really random where youll find the good stuff. you didnt post your location but in bay area, california theres a trailer goin for $100 :
http://sfbay.craigslist.org/eby/boa/200396662.html
good luck