adding a word to a line

[http://sevillejewelry.com]

I have a list of keywords for google adwords, thousands of them. i
simply want to add the word "buy" before each phrase.

currently, each line has one phrase, for example

platinum ring
platinum sapphire ring
platinum ruby ring

is there a way to insert the word "buy" at the beginning of each line,
lets say i select these three lines by highlighting it in black? i
don't want to literally type in buy thousand of times, the end result
should look like:

buy platinum ring
buy platinum sapphire ring
buy platinum ruby ring