I started with a pretty basic brass pendulum and honestly it was enough for me - I think it's really your personal connection that matters, not the material. Plenty of people will tell you crystal is "more powerful" but there's definitely a lot of marketing involved in that 😅 what really matters is that you feel good with it, that you like how it looks and that it's not too heavy to hold for long without tiring your hand.
If you're just starting out, I'd say skip the expensive stuff for your first try - get something around twenty euros or so that speaks to you, test out different shapes (pointy vs rounded) and see what works for you. As time goes on you'll understand your preferences better and then you can invest more if you feel like it 🔮