AC Power cords, which components 1st...?

I agree with Sugarbrie ... at least as far as starting with the CD player/transport first, before the preamp/amp/integrated. The old saying about "garbage in ... garbage out" is certainly true in audio as well. If you send a dirty signal to the amp, you will just amplify the dirty signal. So, at least start with the CD player, and then work towards the end of the chain.
The same rule applies to purchasing components, you buy the best source component that you can afford. Then you buy the best amp you can afford. And last, you buy the best speakers you can afford. William Z. Johnson (truly a pioneer among audio manufacturers as the head of Audio Research Corporation ... and a most credible audiophile!) long before ARC had a source component to offer, and before the days of CD, made that astute observation. He said that you should start with the best cartridge/tonearm/turntable you can afford, and then buy the best preamp, and so on. That statement in the context of things, was a very honest approach to starting someone on the right foot in audio!
The only reason I hesitate about making the power conditioner the first component to replace the power cord is because it should be cleaning up the line voltage within itself. But, I won't argue that point until I've tried it myself ... I have tried the other and know!

Between the DAC and Transport which would be first.

The Cheapskate answers:
Don't fret about it. Keep a look on audiogoN and buy one each of cables as they come up for less than $70 each including shipping. Play around with each cord as they arrive. Cords are very system specific. With the law of diminishing returns, if you haven't already jumped into buying power cords, then your system isn't ultra expensive class A already, and the benefits to be had from power cords at the upper range of your price guidelines aren't likely to provide significantly superior sonic results.
So get a variety of sub-$70 cords. Switch them around. See what sounds best and works best for you. This way you can do your entire system for close to what you have budgeted for one expensive cord. Let your own ears decide.

I disagree with Brtritch. One need not have a class A system in order to appreciate the addition of a top flight pc. Of course, placing a $1000 cable on a $500 component doesn't make much sense either. Having said that, I have heard expensive pc's make profound improvements in modest systems.

My recommendation would be to go to a service oriented dealer and audition some pc's. Try the cables on a couple different components. Then decide if the pricier cables seem to be worth it. Keep in mind that pc are very component dependent. Next, borrow the pc's for an in-home audition. My personal experience suggests starting with the amplifier first but as long as you have the cables at home, try them on different components. Also, keep in mind that high capacitance pc's can cause problems in a system. I've had some that created power supply transformer hum and system noise that was audible from the listening position.

For what it's worth, the $340 Shunyata Sidewinder Gold pc on my monoblocks made the single biggest improvement in my $30,000 of any upgrade I've made in the last couple of years.

To answer one of questions about where do you first put a powercord on the Dac or Transport in the majority of systems the transport has a much larger effect than the Dac.
But as with everything in Audio there is no absolute. We have found a few rare cases where the Dac has a larger effect.

A powercord greatly improves the effects of a line conditioner.

Shunyata Research has just come out with the best Audiophile powercord that I have ever heard under $200 the Diamond Back at a retail price of $150. Having said that let me also state that I am a Shunyata dealer. But I have just finished listening to them for over a week and they are very good. Better than I expected them to be at the price point.

Also, do not be surprised, as have so many Audiophiles' before you, that once you experience the effects of upgraded powercords in your system that suddenly your budget will rise.

Good luck you are in for a surprising experience.