Depends on how "serious" you mean...I've dropped around $1500-1700 on my current gear but I don't get to play every weekend and I'm not such a fan of speedball...but I love playing.
I used to be very serious about it. Had a 3 man team, played every 3 man tournament around here. Had an angel a4 with halo b hopper. this was about 2-3 years ago. Haven't played so much lately.