Looking for a good knife sharpener. Needs to be able to do both straight and serrated blade. Would like to stay under ~$40 if possible. I've seen ones at Dick's for around $10, but I can't help but feel a 'get what you pay for' vibe off of them. The guy at the store says it's the one they use to sharpen their knives around the back of the counter, but...still feel like it's gonna be garbage.