Stranded, shielded (STP) Ethernet cables aren't a bad investment for sensors. Chop up a few patch cables, or buy it by the box to last you for many years.
Most of the custom circuit systems teams run in FRC don't really care too much about signal integrity, but it's a good habit as you implement more and more complex designs, especially if they operate at high frequencies, or can pick up stray RF energy over analogue lines.