There is sound advice in both the above answers and 98Z5V is 100% correct the Lapua is not that expensive my thread on it's cost was me being sarcastic and attempting to be somewhat funny, but the truth is 1 lb of powder will load 70 to 75 rounds brass as 98Z5V said cost 400 bucks BUT I went to scheels to get it and found that if I got their visa card I got 30% off and another 10 percent made on purchases that day I got them for 265 bucks , what I am saying is look for deals they are out their. Bullets that I shoot are 1 dollar a piece Berger 300 grain OTM Hybrid Tactical that is not the only bullet out their hornady 285 ELD match are way cheaper A tips are the same price as the Berger's....I am probably loading Lapua rounds for around 2.40 cents a round ...but I made the decision to shoot that round for many reasons and the main one was I still have a lot of distance to go with it .
Calibers lets talk you have three classes of calibers marginal, finesse, and big boys, marginal are the 6GT, 6.5 Creedmoor, 308, ect. finesse are 300WM 7Mag ,7PRC ,300PRC, and even 338 Lapua, Big boys are 375 Chey-tec 416 Barrett 408 Barrett, 338x378 with one off bullets 50 cal ect.
What do all the big events like king of 2 miles shoot? big boys and I can not afford to build one much less feed one so I chose the finesse class and in that class I chose the biggest I could afford without mortgaging the house so what you want to look at is how big of a bullet can I send downrange with any given caliber, that is the key that is how the big boys win big bullets. I shot the mile with my 6.5x284 Norma it shoots a 140 grain bullet at 2980 it would be easy to do on a windless day that day I had to hold 12 to 14 min. of angle wind!!!!!! with the Lapua in the same wind 3 Min. it is big bullets that get it done in the wind.....
So lets talk 7 PRC as a stock Caliber for ERL i really do not see it doing much past 2200 to 2500 simply because of case capacity the bullet will do it for sure the BC is awesome but can you launch it fast enough ? i can not really say BUT I do have experience with another 7mm the 7 mm STW now that case will hold a lot of powder and would be a match for the big 190 grain bullets brass is available all you have to do is get a Remington 700 action or gun in 7mm STW and have it throated to allow for the big bullets and you would have the very best the 7mm can offer and you will not break the bank...IMO
If your goal is 2k and you are not worried about 2500 and 3000 (like I am) then I think the 300 win mag would be the most economical choice you are still going to need a chassis and weights to bring the total weight over 20 to 24 or so lbs to keep that bitch from beating you upa and I think a sendero type barrel in th 28 to 30 inch range will add some legs that keeps the barrel cool and that is a problem with the thin stock barrels Heat! anyway my 2 cents if I can help you in any way just drop me a line more than happy to help.
P.S also look at 28 Nosler but my point to all this is a 300 win mag and a 7mm prc both launch the same type bullet (190) at about the same speed so whats to gain? A little bit of BC......IMO