unless i am mistaken, the Leaguecraft builder is adding a percent of the level 18 attack speed (1.013) instead of the base attack speed (.67).

going to make a practice game to confirm this.

EDIT: confirmed. attached is a screenshot of the stat box of an in-game level 18 Tristana. no attack speed runes or masteries, four daggers (+15% attack speed each) and two recurve bows (+40% attack speed each) make +140% attack speed. the top box shows her without Rapid Fire (1.887 AS) and the bottom with (2.477 AS).

Berserker greaves, malady and starks gives you something like 2.3 attacks per second with rapid fire. Dont see the need to get anything more than that.

i contacted the individual who runs Leaguecraft and let him know of the aforementioned error.
the error has been corrected and if you check out Basilisk9466's link you will see that +140% AS now correctly sets Tristana's AS to 1.9

Nice one dude. Surprising that nobody caught this before, really. Glad to know it was my understanding based on the Leaguecraft numbers and not something else I was doing wrong <_<