The larger the screen the higher res you want, otherwise you have large distracting noticeable pixels. Just look at a tv, usually everyone has seen like 40+" 1080p. Go up close and you can easily see the pixels. But if you are close to a pc monitor with smaller pixels it's not so easy. You tend to be close to pc displays hence the need for higher res. You won't afford a 1440p monitor on that budget. A good 24" 1080p is ~$160. 1440p is going to be $500.