Few years back we bought some LED lights for the patio. Had them sunken into the ground so they are level with the stone. They're water-proof as they come in a sort of shroud/hood. Pretty simple to change the bulbs if required - we haven't had to as yet. Can select standard white bulbs or colour changing ones and give off enough light to create a nice mood.
Can't remember how much they were now.
Quite simple to get wired in too.