For $3,000 you have a ton of choices. As mentioned, I'd avoid the Savage based on re-sale consideration alone. However, it'll be tough getting your money back out of custom firearms for the most part so choose whatever floats your boat.
From your comments it doesn't sound like you've put a great deal of consideration into caliber choice. There's a huge difference between the .308 Win. and .300 Win. Mag. on just about every level. Here are just a few things to consider.
Choice of actions (short vs. long)? Long actions are marginally more expensive but basically moot point over the over-all life of the rifle. Biggest consideration here may be weight. Especially, if this project will be used for hunting.
Recoil. If you don't have much experience in this area, a .300 Mag. is gonna' beat you up big time. How long are your range sessions going to be before fatigue or flinch sets in? Maybe 30-40 rds.? To help negate the recoil expect to buy a muzzle break, an exceptional recoil pad, and a stock that has a heavy fill.
For extended range sessions where more than 50 rds. will be fired at a setting, a .308 Win. will be far more forgiving in the recoil department.
Component costs. .300 WM brass is more $$$ than .308 Win. and match type brass is comparably harder to find here in Canada. Brass life will be considerably shorter as well, especially when you're loading hot.
Bullets. Basically, if you plan on shooting a .300 Win., you'll likely be shooting a heavier match grade bullet that'll be slightly more expensive than 155-175 gr. match bullets. Not a big expense but availability will be a bigger concern.
Powder. You'll be using a lot more with a .300 Win. with approximately 80 grs. of powder to a .308 Win's of around 45 grs. Powder expense will be almost 2x with the .300 Mag.
Primers. Magnum primers are slightly more expensive but not by a big margin. Availability may be the big issue. Buy them by the 1,000 when the opportunity arrises.
Barrel life. A .300 Mag. will have an accurate barrel life around 1,500-2,000 rds. compared to a .308 Win. of approximately 4,500-5,000. How much shooting do you plan on doing? Replacing barrels is not exactly a cheap endeavour.
Shooting distances. If you routinely shoot or hunt at ranges less than 600 yds. does it make a great deal of sense to go to all the added aggrivation of a .300 Mag. when a .308 Win. will do the job more efficiently far less cost?
Hell, if you just want a big boomer to play with, then go for it! However, if it's a regular shooter, you may want to give caliber selection some greater thought first. Personally, if I wanted something that hits harder and has greater range than a .308 Win. without being hard on barrels I would select a match grade .30-06 Springfield with a 28"-30" barrel shooting 185-220 gr. bullets.