Source of RJ-45 cables for connecting FLARM, K6 Mux, etc.

I'm curious about the type of RJ-45 cable needed to connect
various .icg-compliant glider instruments, such as a PowerFLARM, K6
Mux, PNA, etc..

First, are the RJ-45 cables (assuming no special connectors or
requirements, just power and data) straight through or crossed?

Second, can regular Cat 6 Ethernet cables be used, or do they have to
be shielded?

Some of the prices I've seen for what appear to be straight RJ-45
patch cables at glider equipment dealers are a bit breathtaking
compared to computer cable stores so I'm wondering if I've missed
something!

Any advice would be appreciated.

Kirk
66