Say you are planning to kill someone. There was a $5 knife and a $50 knife but you picked the $5 knife. Why did you choose the $5 knife

Just to be clear o have absolutely no intentions of pre-meditated murder of any kind, this is just a hypothetical scenario on how to potentially get away with potential murder. Potentially.
Moving on, it’s a matter of disposing evidence, and spreading suspicion. Now, chances are, I won’t care about having to ditch a five dollar knife, which will be made with inferior materials. Second point comes from the first, which is cost. A store keeper will most likely forget a guy buying a five buck knife with cash as opposed to a fifty dollar knife. (Cash to eliminate trails.) From there, there are literally millions of five dollar knives produced and sold daily. If I buy from a store that specializes in knives, or at least has a significant knife selection, chances of them remembering who bought one of the thousands of cheapo knives sold that day are miniscule. After the actual deed, I either hide the knife, (find an construction site, and bury it beneath some gravel to be paved over, or drop it into the foundations or a cinder block wall. Slim chances it’ll ever be found.) Or destroy it by either melting it down or with acid, (which I can get pretty easily, like on breaking bad.)
Now this would be me buying a knife, but to be honest, building one provides a harder trail if you know what you’re doing, which I do.
I’d begin a knife, relatively large, and preform the deed. Upon my return home, burn the blood and other viscera off and get to work. Using an angel grinder, or by heating and hammering, make it thinner. Then, cut it down to less than half of the original size, and give it a new edge profile. (I would start with a mini Xiphos and re shape into a Tanto for example.) And then, cast the cutoffs into an ingot and send it to the recycler with the rest of your I gotta to be recucled. If interviewed, say that the knife description sounds familiar, and you’ll have to go through notes. From there, supply the design and make sure that you’ve had these done at least a year in advance, and say that you designed the knife and had tried to sell it at a garage sale a few weeks ago, but at the end of the day had found it stolen. Then offer anything that they ask for, metal supplier and the type of steel it was made from, as well as the designs. As for the actual knife? Sell it or destroy it, doesn’t matter, what does matter is that the original shape is not any where outside of the plans you give the police, and that none of the metal exposed on that know had any contact with the victim. After the cops are gone, who cares. I would recommend selling it a long ways away, at least out of jurisdiction, or destroying it. Do not keep it or sell locally, too much risk involved in my mind. Complex, but airtight. Cause you are helping the police, throwing off forensics and either helping the environment by sending the evidence to be recucled or to be added to a collection in another state.
I still wouldn’t do this, it was a late night conversation between friends. “If you wanted to get away with murder, how would you do it?” Was the question.

Mossy Oak Survival Hunting Knife with Sheath, 15-inch Fixed Blade