If I remember correctly, I believe it is randomized on a per-bot level but the team tends to have a pre-configuration. For example, I find that some bot on my team when I'm playing as Counter-Terrorists will always go for the M1014 shotgun. The bot that chooses it changes, as with the names, but generally the weapon configuration for the team is usually the same.
However; it also does change according to your team's economy. For example, I've noticed that if our team economy is doing pretty well and we have extra money to spare, bots may start buying the semi-auto sniper rifles, and sometimes 2-3 of the bots at a time will do this. On the other spectrum, I've seen bots that will buy the Galil or SMG's when our teams economy is not as strong as it could be.