It just simply means that you're not used to using very head heavy racquets like the AT700 and the high momentum carry over after your swings are putting stress on your wrist. Go get some more training or switch over to something more friendly yet similar like the Apacs Tantrum 200.
maybe your pushing it too far? i.e after the moment of impact(with the shuttle of course) you should be relaxed and not still be adding energy...
This was the same for me when I transitioned from NS8000 to a MP100 and AT900p. I was slowed down tremendously and my wrist hurt. I fixed this by just picking up my racket every day and doing a couple of swings.
prolly u'd like to try the Finnex raquets range ? i'd say the infinity series is ok,and the prices are 'way' below your budget !! i have Infinity 9000 at less than Rm 300.. that'll be about USD 80 plus or so !!