Development kits are expensive due to low sales volume, no cost optimization, and buyers' price insensitivity. There is a huge amount of value in having a known good implementation on hand when designing hardware or firmware. Additionally, having the development kit means your firmware team can start developing before your hardware arrives.
If you have a good relationship with them, sales reps will often give or lend development kits.
If you have a good relationship with them, sales reps will often give or lend development kits.