Dr. Collins. It is $350 new, but a lot of people sell it used in the market place. Make sure you get the most updated version. I got a 79% taking it (88% in chem, 84% in bio, 83% in verbal, 78% quant, 25% in reading... I didn't study for reading because I was doing excellent on the practice tests) and I only have a 2.71 GPA.
Official PCAT practice tests on the Pearson website. It is $80 for all 3. It is very similar to Dr. Collins, but it is worth it to see where you will most likely score.
A lot of people recommend Kaplan PCAT for biology. I bought it, but only read through 3-4 biology chapters. It is only like $20-25 on Amazon, but I would skip over it if you already bought Dr. Collins and think that is enough.