So according to
this thread, for its time TOS was quite an expensive show to film. Just had to say it to fight against the misconception of it being a "low budget show"
According to what I have read, a lot of the special effects on TOS involved lights and gel packs. Different colors of gel packs were used to illuminate the skies of alien worlds, for example. Gel packs were also used to illuminate the long tubes that doubled as the warp engines. TOS was very into bright colors, like no other show before it.
Matt Jefferies was the Art or Production Director at Desilu. He was given the job of creating the Enterprise. There was just one problem. He had no budget. So, in his words, "I spent some of Lucy's money" to buy what was needed. Lucy, of course, was Lucille Ball, the owner of Desilu. Jefferies would later create the Klingon and Romulan spacecrafts used in the series. The famous "Jefferies Tube" in the Enterprise was named for him. He actually built the thing.
The biggest funding issue came at the end of the first season. Star Trek was catching on. It was enormously popular with children and young adults. Its biggest star was the "guy with the ears," or Spock. NBC did its level best to cancel the guy, but the network tune changed when NBC began to receive fan mail from kids who wanted to see more of the guy with the pointy ears.
Leonard Nimoy knew this. He also knew, for the first time in his acting career, that he was a hit. An absolute smash. So he immediately demanded a huge raise. He wanted Shatner money. He wanted all of Shatner's perks. He threatened to hold out until he got what he wanted. It became such a distraction that Roddenberry nearly wrote him out of the show.
So, yeah, the show cost money. It also had to change at the start of that second season when Spock had to get the same amount of screen time and importance as Shatner did. This did cause a bit of a rift between the two.
