I'm coming up with 519 AP when I'm calculating with an Elixir. Keep in mind I said that sometimes I actually run a 100 AP rune/mastery build (scale to 18, gain 5 AP/level), because Evelynn does not need Armor to farm jungle because her passive heal supplements. It does make her a paper tiger on pushing/tanking a turret, but the trade off when running some tanky items is immense.
I'll say it again. I don't ALWAYS play tanky. There's just some match ups where it seems like the better choice. For example, vs a 3-4 tank team, Eve really is at risk of getting cc'd down to the point no matter how high your AP is, you won't get the chance to often use it because she will die before she even gets free of the cc to ult.
In fact, one of my most successful games was :
Hunter's Talisman > Wisp > Boots of Swiftness > Luden's Echo > Lich Bane > Rod of Ages > Void Staff and Finally a Hextech Gunblade. Not much in the way of CDR, but the assassinations were purely oppressive, and that was vs a bunch of champs which SHOULD counter Eve: Jayce, Sivir, Amumu, Cho. That game I just went pure AP because by level 8 or so I was 10/1/8. By the end of the game I was 20/4/12
But, You can't always do that.
There are at least 80 Champs in league that can make pure AP eve hell.
Sometimes my only tank items are a Banshee's and a Zhonya.
Other times I do those 2 + a Iceborne.
Or in a game where I have a really high burst high stick adc like Lucian, trade the Iceborne for a Frozen Heart (because he's going to go Lord Dominik's, so it's better to have less HP and more armor)
I was originally a fan of "as high as I can go AP" too. But, there's just so many instances where a high AP Eve gets shut out of the fight. In a team fight, if you only have 2k hp and 808 AP, you're going to die the second you try to Q poke, because the other team has skills that are longer than an 800 range. And a High AP Eve can't rightly utilize her E unless it's a solo kill. She sucks at turret pushing as well.... so if you're vs a team that makes pure AP Eve useless, you've pretty much handicapped your team to a 4v5 with the occasional last second Eve burst. I mean.... at that point.....a Jungle Ezreal is a better pick, even though that's just a super troll jungler.
I've even moved away from exclusively using Mobis, because most teams expect them now, and if you have Mobis, and the other team RG's you or has built in long range poke, your Mobis won't help you escape a fight anymore. You can R, but there are ton's of champs that catch up to R, like a Karma or Sona. I'm finding a good Karma is a NIGHTMARE for Eve.
And this is live testing. This account's MMR is already shot for this season because of my initial 20 or so Eve games getting dominated by Jarvan /Xin Elo boosters, and it's only getting worse as frantic low elo people are paying for boosts to gold before the season ends.
I haven't had any real Eve "Failures" yet, imo. Even the losses have usually been stalemates for me, or if negative, only slightly so, usually due to my team feeding when I'm not there, or snowballing an elo booster. They feel like wins by how I played. And, about the last 15-20 games have REALLY felt good, like I had a zone. I'm still scared of Jarvan, and I hate Sona games atm (manageable but if built right she's really annoying in preventing assassinations), Kha Zix games, and Nasus games.
I've started playing around with a Stonepact build just to get the Extra Tenacity/Slow resistance vs a Nasus, and it seem viable enough. He's really broken after the Sterak's change (Trinity + Steraks = hardest hitting slow in the game coming from the only champ with a .5-1 second skill during ult that can do 1500-2k each hit, who also is almost immune to cc. Takes away Thunderlord's, but leaves me with much better cc game survivability. That'll change with runes though.