Re: Nebie die question...
Unless you have a top grade custom barrel and a quality high power scope on your .308 then a basic two die rifle set is all you will really need for a very long time, if ever. And, given that all dies are made to meet standard SAAMI ammo specifications - and that's a range, not a specfic measurement point - there's as much average variation between dies of the same maker as there is between makers. About the only thing the price of anything tells you is it's cost.
I suggest you consider a Lee Delux set to start with. It's a three die set that includes a standard FL sizer, a very good seater and an excellant neck sizer plus a "free" shell holder that others charge you for. That set will let you play with neck sizing when you want to without paying exhorbatant cost for "competition" dies you may find to do you no good anyway.
The limiting factor to the quality of ammo you can make with any die set is mostly your own skill. It will take you a long time to get better than standard dies - after all, they ARE pretty good. Then, IF you ever get the itch to buy more costly dies you won't have spent excessively on your first set and you'll have the personal experience to wisely select what you want to try.