Best Bang for the buck would be to go with Stiller. Any custom action for that matter but the Stillers are least $$ of the custom lot and are top notch, and you are asking "bang for the buck" so I am going with lowest cost best quality. I have said this elsewhere recently, after much experience building 20+ rifles on trued 700s, and many of them being as accurate as any custom action based rifle I have built, I would never waste money on truing a Rem 700 again. You will spend the same amount of money as the Stiller or possibly more, and it will be worth $400 bucks when your done. Buying a "trued" 700 does not mean you are getting a custom quality 700 action, and I personally, would not pay $600 for a trued 700. I have seen firsthand, trying to sell trued 700s myself, that there are VERY FEW people that will pay that. IMO it would be foolish to pay $600 for a trued 700 when you could have a custom for @$400 more. IF you ever sell your Stiller based rifle that $1000 action will be still be worth right at $1000.
Don't misunderstand I am not saying trued 700s are bad or not a good base for an accurate rifle. I am saying from a money standpoint, back to bang for the buck statement, it is a poor investment to use a 700. A basic $400 blueprint of a 700 does not get you close to meet what you get from a off the shelf custom action.
1.Blueprint
2.Sleeve bolt and ream raceway
3.Bush firing pin hole to .062\ turn firing pin
4.Check scope base holes, weld up \re mill to true centerline of raceway, VERY COMMON PROBLEM that is rarely fixed and cannot be fixed by simply drilling\re tapping to 8-40 screws.
5.Install Sako extractor
6.Fix bolt shroud drag, not always needed
7.Remove and replace bolt handle for proper timing, not always needed
Items 2-7 cost extra, on top of the standard blueprint, out of your pocket and are worthless to any future buyer or the value of your custom firearm. A fine shooting rifle can be made on a 700 but after you are done with it, you love it and have spent $2000+ dollars on it, wouldn't it be comforting to know that your fine custom rifle is actually worth the money you have invested in it, even if you never intend to sell it? For me anyway it always eases the pain to know I can re coup a large portion of the money I have in a rifle if I ever needed to sell it.