Hey Ellis. Thermal compound isn't something you need to invest a lot of money in. You may shave off 2 or 3 degrees. The main characteristic you should care about is conductivity. For CPUs, this isn't very important but it is a safety feature in case any paste spread past the heat spreader (the metallic cover you see on all CPUs) and onto the motherboard. This isn't a common occurrence and shouldn't be a major concern for you.
However, on the GPU side of things, non-conductive thermal paste is a must. If you ever find yourself with an overheating GPU and feel like you want to replace the paste, you will need to have non-conductive thermal paste so you don't fry your chip. Also, make sure you have the correct thermal pads (thickness is important here; you can't use paste in place of pads). That is another undertaking so if you ever decided to do that, just be aware of the differences!
I think my GPU is alright for now, but great advice. Thanks!