Can I get into KMC Manipal if I score in between 200-300 in the NEET and pay the required amount they ask for?

A score of 200 to 300 will get you into KMC Manipal only if you enter KMC through NRI quota. Non-NRI management seats cannot be secured with such marks. You need at least 550+ for those seats. Moreover, NRI seats are very expensive so look up the fee structure once. 

If you are not an NRI, just show some NRI background by making one NRI relative your sponsor. However, I will advise you to score higher if you want to get admission using the management seats.