I've played a few hours into the game and I've been more or less following the main story missions. Right now I just solved a big problem for Vault City. I want get some better weapons but the prices are enormous. Is there a good way to "grind" for money and/or equipment at this point? I'm level 8 with a focus on small guns and melee (+ 3 followers) for combat.

Depends on your skills. If you're good enough, gambling in Reno is a very reliable way to make money.

Skinning geckos is one way, especially golden ones. (if you're good, and have completed a certain Klamath quest.)
Killing small groups of slavers/raiders can be good, if you're strong enough to carry all their equipment.
If you're evil, you can take the short-term benefits of slavery. (also, plenty of theivery and killing traders/farmers etc.)