Mainly, it’s to make sure that you’re not infringing on someone else’s work and to do your due diligence if you’re seeking to apply at the US Patent and Trademark Office. While filing through a patent attorney is probably not a bad idea, you can do all of the work yourself. Last I saw, I believe a trademark ran about two to three hundred dollars. Patents were a bit different depending on what stage you were in and what you were patenting.
Either way, you still need to make sure that you’re doing the right research. There are several searches online that you can use, and some are better than others, but I would definitely recommend from a preliminary standpoint to first check Google Patents. This is the quick and well-known text search method similar to their usual search engine. Pretty remarkable look. From there, I would go to the USPTO and be definite that you’re not missing anything. While Google makes the effort with updating their databases, there’s nothing that screams finality than going directly to the source.
There are other methods of searching, some are a lot cleaner that allow complex regular expression, but overall, I would recommend at the very least doing the two above. That way, you’re at least covering yourself and making sure that your business won’t be forced to change its name in the future because someone forgot to do the legwork.