go to the IBS website, there were two 1000 yard clubs in Mid and SW areas.
http://internationalbenchrest.com/ranges/usa_by_state.php
St Louis has an IBS 600 yard club.
Go to the matches first and look at the guns etc. 600 Yd nationals are in SW MO this year, 1k Nationals at Hawks Ridge NC
go to the 600 yard nationals, lot of guns for sale.
IF you are going to shoot 600, then buy a 6 Dasher or BRX, they will work for 1K also.
I would buy a good used first. Look at the matches and on 6BR and Benchrest Central. You will save $1000-1500. Might call Bob White at Shooters Corner as he stock a hundred or more BR rifles. Stay with the Dasher or BRX though.
Shiraz at bullets.com will have factory Dasher brass this summer and just got in the first run of Nosler 284 brass.
Build later, a top notch gun will run $3500 to build.
BAT MB melonited with roller cam and Dwight Scott firing pin mods- $1500
Brux HV with 7.5 twist (they have found 8 is not quite fast enough for some bullets) -$320
Stock (Shehane tracker, Hammerhead or Lowboy) -$700+ finished
http://bulletin.accurateshooter.com/2015/06/hammerhead-stocks-for-long-range-benchrest/
Trigger Jewell-$240 or new Andy and Bix-$400
Buy your own reamer- $160 email me and will give you a reamer print # from PTG
Bostrom Gunsmithing RAS tuner brake -$240
Chambering- $200 plus
Bedding- $200
Misc, trigger guard, butt plate -$150
Dies- $200 Whiddens match with the reamer print I have
Rear Bag-$150
Front rest with joy stick-$800-1300 Call/Ernie Bishop on this site to get on the list for a SEB rest if you want the best. Only 1 year wait.
Good 6mm bullets are running $.55 to .75 EACH also.
Bostrom Gunsmithing did a 2 week turn around on my Dasher and only had to wait 3 weeks after calling to send it.