hey scrod, can we ask you any type of question? if yes here's my question

what would you buy if you're looking for a fixie and have $600 to spend? would you build one up or buy a complete? research has led me to kilo tt or premium brew as members have suggested. I will not be racing this bike, it will be for flat city riding no harsh uphills. I am mainly a mountain biker with my yeti 575 but wanting to joing other crowds who does road bike only. I was in the retrogression site and saw the sexy looking bikes and wanted to get your opinion on it. thanks in advance.