I had been using Avent bottles for DD but wanted to switch to bpa free. I was worried she would have a problem switching to a new nipple. I found these bottles at BuyBuyBaby and the switch is working out great. I found the nipple on the ThinkBaby bottles was the most similar to Avent.

If you use a non expired Bed Bath & Beyond coupon you can get 20% off.

You can also order them from here:

http://thinkbabybottles.3dcartstores.com/