What will your training regimen be like/based on?
I was in a similar predicament earlier this season, and decided to max out my budget on a bike that I should be completely happy with for multiple seasons, and will buy a power meter at bonus time before next season. I am training with a team where most of the riders are in their first season of racing, and we have a coach who gives us workouts which measure effort based on HR. He recommended that I not worry about the power meter when getting the bike, and wait to shell out until before my second season of racing. YMMV...depending on how you are training and who you are training with, either option may make sense for you.