Unfortunately, there is no quick answer.

$700-1000 sort of limits you for building from scratch. Buying a-la-carte is always the most expensive way. If money is an issue, then you could either try to luck up and find what you want used, or buy a complete new bike and upgrade it as things break or you get extra cash.

Also, you may be a candidate for a road bike. There are lots more road bikes on the used market than fixed gears. 6'0" puts you in the 56-58cm range (just guessing). The coming fall and winter are great times to buy a bike because demand is low. To put things into perspective, a new Trek 1.1 road bike is less than $700. $1,000 on the used road bike market can get you a really really nice bike.