I wouldn't even bother paying money for antivirus software. You can run a combination of AVG and Malwarebytes for free, and still maintain a healthy computer.
It's very unlikely that you will find a laptop with the requirements you want for that price. Most I've seen with the specs you are looking for run for at least $1000, and that's if you can find a good deal.
That shouldn't be too hard depending on where you live. If you live in North America, check out Best Buy or its website. They usually got pretty good deals on laptops.