What to do with very low offer on an item for sale

@retiredaudioguy one more important note - when you accept PayPal goods and services you get hit with a fee and there’s a chance for scammers to pay you and then charge back claiming some nonsense with PayPal who typically side with the buyer. Be very careful with buyers who have no feedback or who registered around the date you listed your item. Just use caution. 
I would strongly advise accepting PayPal Friends & Family only especially for the item you’re selling which isn’t high dollar by any means. There are a lot of counterfeit cardas cables and that’s what someone can claim. You don’t want that headache. 

I always acknowledge any offer and I will say to people thank you for the interest, but this is the price and then I just move on

Give them an answer. I don't understand 'ignore'. 

Many thanks for your input.  I think I'll be polite and respond "Thank you for your offer but it is too far below the component's value for me to consider."

One of my indicators is the buyers feedback history. That alone should tell you what they’re about. As stated above most low ball offers aren’t from serious buyers. For me I tend to mirror the person asking , if they’re rude I don’t respond, if they are not rude I give them the benefit of a polite response as you indicated above. Regards , Mike B.