The other thing is the smallest Conductonaut syringe is typically enough for approximately five applications. So that $15 is more like $3 per application. Peanuts in a budget for your average $1-2k PC, and probably one of the cheapest ways to shave 5°C off a cooling system with enough dissipation capacity to actually get rid of that heat. That's another point, unless you actually have the radiator/heatsink capacity and efficient means of getting the heat to that, before getting it out of the case, LM/Conductonaut only removes the Chip/coldplate bottleneck. This is probably one of the reasons some people have 10°C+ improvements, and others only see changes within margin of error.
One of the most common mistakes people make is using way too much LM on application. You should have as little as possible while maintaining full coverage applied to both the chip and the coldplate. You want a chip sized coating on the coldplate in the right spot, and a full coverage coating on the chip.
You can't simply use the typical thermal paste application method, putting a dab on in the middle or an X or whatever. You have to apply it thinly and evenly across both surfaces to get ideal results.
It's tricky to achieve this, as it has a very high surface tension and tends to ball up, refusing to spread, especially on a recently cleaned surface, it doesn't behave like a typical liquid or paste.
The way i've had most success after tens of applications, is to use the syringe with the needle tip included in the kit, put a small ball on each surface, then use the included bud stick things to spread, before using the syringe again, in suction to remove any excess puddles of the stuff. This results in a very thin layer applied evenly.