Great guide. Have you considered a Black Cleaver instead of a Last Whisper? ArPen is great, but unless they're building Armor, it's overkill. BC give a nice bit of Attack Speed on top of the Armor debuff. It's just about everything AD Jayce could ask for.

It'll take about half an hour to pay for itself, much less other items.
Use it to crutch your early game efficiently.

I thought it was a nice addition, not just for the health and mana regen but also for the gold.
It helps get that infinity edge and Last whisper a lot faster, as well as the other pricey items in the end-game build.

why philo stone? a vampiric scepter is good for healing and you got a passive mana regenerate skill... but good build ^^