It kind of depends on your budget....
If you have a limited budget, go with an off the shelf rifle like a Savage or a Remingto 700 SPS Varmint. Both are good platforms and you can build/upgrade/improve them as your budget allows.
Here's the write-up of my 308. Read it all the way to the end and you will see it transorm into a full-custom 260....
http://www.longrangehunting.com/forums/f53/my-308-1k-rifle-evolution-continues-43510/
Although my rifle is a Remington, you can do similar type of upgrades to a Savage.
In terms of caliber, I think you can get a Savage in 6.5x284, but you are right that it is a known barrel-burner. So another caliber may be a better choice if barrel life is a concern for you.
It would be helpful to know your intended use to give a more informed recommendation on caliber. Given that you said 6.5x284 I will assume you will be hunting deer size game or smaller. In that case, a good 'beginner' caliber is 308.