A higher voltage has several advantages over 12v - voltage drop is reduced which means that you can get much longer lengths before the brightness begins to fade plus they operate at a lower current which means reduced heat and greater long term reliability.
If you do want 12v Strips for more economical installations click here
Watch a video about using No Solder LED strip here
Quick Form means you can order all parts in one place, quickly & easily - here
If you buy in full reels of 20 or 30m then you can get BIG savings HERE