For a entry-level gaming mouse the Razer USA Razer DeathAdder 3500 dpi
is one of my absolute favorite options. At the $100 mark it's a fair price for what you're getting with the speed and dpi sensitivity. The longevity varies, I've gone through two in seven years personally, but I know people who've had one just as long, and people who go through them in months. I used this mouse to hit diamond/challenger in league in s2/3 and have been able to be in the top 100 NA in PUBG with it as well. It's definitely good enough to get into professional-level gaming and more than enough to get started!