I generally wear just 1 layer. A good single layer sock such as Thorlo or Bridgedale should be perfectly fine.

Currently I am using these Thorlos;

http://www.thorlo.com/socks/hiking-socks/crew/59.php?color_id=72#A

For me they have a nice comfortable fit and have the appropriate padding in the correct places.

I will also take a pair of Goretex socks such as these;

http://www.wiggle.co.uk/p/PriceDrop/12/Gore_Gore-Tex_Waterproof_Socks_2007/5360031431/

together with an a spare pair or two of extra Thorlos (i.e. dry evening or trail change).

Keeping your feet dry and free from hot spots (because or boot rubbing due to incorrect boot fit) is the key to not getting blisters. If your beginning to get a hot spot its best to stop, remove your boots and apply a Compeed patch and then change to a fresh pair of socks (you may even need to wash and dry you feet properly before changing your socks. Even letting your feet cool down in a cool breeze for 5-10 minutes will help ). Let the first pair of socks dry out (attach them to your BOB or pack to air) then put your boots back on to proceed. Try to do as much before hand before letting a blister develop.

Boots and socks aren't really an area to be economical and save money. Best to go for the best boot fit, no matter the cost of the boot and try lots and lots of boots before you find the pair that fits properly. Also once your happy with the initial boot purchase it might be worthwhile purchasing a couple of spare pairs a few months later because chances are your not going to be able to get them a few years later.