Any recommendations on ordering air tickets Newark (New York) – Lima – Pucalpa (Peru) flying at the end of December?
Any piece of advice regarding prices, time, websites, etc. is greatly appreciated!

It is much better to fly to Pucallpa. Book your international flights and then look for local flights on a search engine such Google. Star Airlines appears to have a reasonably priced daily flight Lima to Pucallpa.

If you can go thru another NY airport and don't mind a layover you can try Jetblue or Avianca to Lima.

I know United flies nonstop from EWR but it will be an expensive ticket if around the holidays.