Got my "Winchester" safe at Sam's Club -- Similiar to Costco but from advertisement's Costco has much better selection -- They are not the best safe but pretty decent.
Advice is to determine where it is going and get the biggest safe that will fit in that location, but make sure it will fit through all the doorways and house obsticles.
The best money I spent was hiring a professional safe mover -- for $150 he picked up the safe from a Sam's Club 40 miles from the house and delivered to the basement. He laid down plywood on the tile floor to protect and did a great job. To move to the final location I used wood dowels to roll the safe into position -- I was not ready for the safe since I was putting up concrete board around the safe location to added protection from fire/theft.
The advertised number of guns a safe can hold is probably based on a short muzzle loader -- add bolt actions, scopes, AR's and the quantity goes way down.
I add the following to mine:
-- Battery powered lights, got them as Sam's. Wave your hand in front of them to turn on/off -- they do a decent job of lighting up the interior.
-- Pistol storage hanger for the inside of the door, holds 6 or more guns in velcro holsters. Think I got them from Sportsman Guide but do not see them now. Really increased the storage capacity and keeps most used shooters close.
-- Goldenrod or similiar device, mine in a Browning brand -- heats up the interior so that water vapor does not condense on the rifles/pistols/etc. Safe needs a access hole for the electricity.
-- And after my safe became overcrowded I purchased the Rifle Rod kit to increase capacity -- http://www.amazon.com/Gun-Storage-Solutions-Starter-19-Inch/dp/B00570T3R4 -- which allowed me to fit a few more long guns into the safe. The added benefit is that now I only have to remove 2 guns to get to the back of the safe, versus before I had to remove 5 to 6 guns. Required me to remove the lower devider but no bid deal.
-- And I also purchased Bore Stores for my pistols that I do not shoot often -- http://www.borestores.com/order_online.php?cam=show_cat&cat_id=122&nav=Handgun Cases -- to protect them. Allows me stack them close together and not worry about scratches and great protection from Rust/Corrosion.
UK