Really? I get them with muzzy tips for about $6.

Definitely upgrade a retriever to heavier line. Not for bigger fish, but because the rollers that retrieve the line grab the thicker line better. Retrievers are simple, so less to break, and take a lot of abuse and keep on working. The worst that has happened with mine is the handle bolt worked loose. Since I always carry a multitool, I just had to tighten it back up. On the safety slides, from time to time check the screw holding the stopper. It can work loose as well. Otherwise, have a ball.