I raced in and finished 4 Worrell 1000 s and ground crewed for one. My extremely low budget average cost, trying to make chicken salad from chicken ****, was about $7,000 not counting boat parts. There was a Sports Illustrated article that contrasted our scrape it together team with a/the top sponsor team. I usually picked up a new suit of sails each race as well so that would bump it to $10k. This was 1999-2002. 1998 I ground crewed out of an RV with 5 of us staying in it and it SUCKED, the only good thing about it was John McLaughlin, who I endured it for. The other racer was one of the biggest **** of miseries to ever draw a breath and you would not want to be trapped in an RV with him.
Parts costs will vary greatly on the intenseness of the weather and the weak points of the boats, and don't kid yourself there WILL be weak points, likely lots of them for untested platforms. Complete rudder systems w/ spare castings, spare spin pole, and the various blocks, shackles, and screws are a must.
My advice, don't scrimp unless that is the only way to do the race for you. The more prepared you are (think more $$$ you spend) the more enjoyment you will get out of the race.

Todd Hart
Team Cat Fever

"I said, now, I said ,pay attention boy!"

The cure for anything is salt water - sweat, tears, or the sea
Isak Dinesen
If a man is to be obsessed by something.... I suppose a boat is as good as anything... perhaps a bit better than most.
E. B. White