$/point is how much it costs for each point that a player scores. Dollars per point is typically found in Daily Fantasy Sports (DFS) formats. This is different from regular fantasy sports leagues because you can choose a new team every week and have a set budget to choose players with. You want a player's $/point number to be lower. If a player costs you $100 out of your weekly budget, and only gets 20 points, he costs $5 for every point he earns. However, if a player costs something much lower like $50, and gets 25 points, he costs only $1.50 per point he scores, a much better value.
Fantasy Points/$ is the opposite of $/point, as it is the number of points a player earns per dollar spent on a player. This number you want to be higher. The higher a points/$ ratio is, the higher the player's value plays out to be. For example, a player scoring 15 points and costing $200 means you spent just $0.075 for every point the player scored. However, if a player that scores 15 points costs $100, then you spent $0.15 per point. In other words, when you spend more per point, the player is actually playing what they were worth that week.