Corrected entry: During the show up until now, they make it clear Prue is 35-37. But when Piper and Paige visit Prue's grave, it says 1970-2001, therefore making her only 31.
Corrected entry: In the scene where Paige's coworker Donnie makes a crack at Billy the mail boy about his inability to "tear [himself] away from the cleavage in this section," he glares accusingly at Paige. But Paige was wearing a high-necked red blouse. She certainly looked attractive, but there was no cleavage in sight.
Correction: Donnie is a jerk. He made a mean comment about Paige that probably had more to do with the kind of clothes she usually wears than what she was wearing that particular day.
Correction: In the season one episode "Dream Sorcerer", a nurse in the hospital states that Prue is 27 when she is brought in after the accident. This is consistent with her grave saying that she was 31 when she died.