Level 90 PoB (I use community edition): https://pastebin.com/GBeLF4h6

I'm using ball lightning in a couple places - the main one is in a CoC setup with blade flurry, and also a low level one in my helm with GMP, high-level added chaos, and CwDT. This procs all the time because of the herald of thunder and storm secret ring. I have another CwDT setup with blade vortex and power charge on crit for reliable power charges. That one also triggers immortal cry.

I've stacked a bunch of life and ES gained on attack/spell hit, so I'm basically unkillable outside of one-shots. Aspect of the spider is one source and I'm saving up for an ES on hit watcher's eye to complete the package. My other ring has life gained on spell hit, too. Wasp nest is what I used for most of the late leveling until I got this gemini claw rolled the way I like. I like the mana gained on hit of this claw best because it means I can do no leech maps and didn't need any mana leech on the tree or elsewhere.

Despair is applied to enemies with the herald of thunder and curse on hit. Dendrobate is the obvious choice for dps but if you want more defense you can use kintsugi or a rare with crit and other goodies.

The agony crawler is perfect for applying my withering - this way I don't have to worry about it at all.

For defense I stack things that make me take less damage like immortal call, fortify, wind dancer, and of course the assassin itself. Mistwall is amazing, too.

Nothing was particularly expensive but it took a while before I had one ring with both aspect of the spider and the lgoh. I actually hit this helm enchant myself on the first uber lab I did, which I realize is pretty lucky. The main downside to the build is that I'm using so many uniques I don't have a ton of life. If you see any way to improve it I'd love to hear what you think. The clear speed and playstyle is really fun and I think whirling blades is still a lot of fun and really strong against mobs that like to throw shit at you from off-screen.

This isn't an expensive build - in fact by almost any measure I'd say this is a 'truly budget' build. That being said it's got a lot of uniques so it's not very SSF-friendly.

Fenemus' boots were the most expensive item (~40c when I bought them). Storm secret was 5c, 6L dendrobate was 25c, gloves were 5c, helm is 1c, ring was about 15c and I crafted it further myself. You can use a 1c wasp nest and it works great. The cluster jewels aren't necessary at all, in fact I might remove them.