any type of warranty and specially life time warranties are always limited in nature. limited meaning limited by certain occurancies that will void the warranty.
check what exactly those limitations are with the seller. i havent seen anyone offering lifetime warranties on HIDs anywhere though...and 14000 is a little too much to pay for HIDs unless you are buying the top brand.
Helios, Mclluoclich and Phillips H4 kits go for around $300 so if this kit is comparable in terms of its quality...then go for it.