Beat the game again! Here's how it went down:
Went all-money in the jungle. Was pretty rich by Camp #1. Beat the race and made about ~5 crystals profit, but money in the bank. Bought a star seed.
Picked up a homing seed in the second world. Used it to deal with all the mobs that spawn, got rich from that too. Got through the desert with the homing seed, mostly. Would plant on early so it'd seek out enemies I couldn't even see yet. Ended up rich from that too. Side note: Wow, homing snakes are terrifying. Nothing scarier than planting a homing seed with a snake hot on your trail, just to have the seed shoot inside the snake and kill it while launching debris at you.
By Camp #3 I had about 60 crystals. Spent 40 on a "turns holes into plots" seed. I thought I'd be able to cash out at the bank because I'm pretty sure I didn't cash out at #2, but I could not!
Made it through world 4 using mostly homing seeds and careful movement.
For the final boss, I used all a homing seed to take care of the initial blue turret, then spend homing seeds to clear out a couple enemies, then spent a ton of my crystals on "turn holes into plots" seeds. Since I was down to 1 heart, I spent my new plots on heart seeds, then on star seeds (which I then used to crash into the enemies I thought would kill me most, which were spiders and turrets). Only just now realized that each subsequent boss-damage plot adds another boss beam shot shot at you, so for the third-to-last and second-to-last hits I found myself rolling down into the safe area I'd made by spending a fortune on holes-into-plots seeds.
Never used teleport-to-next-splot, thomp, or boomerang seeds. Used a shield seed once but don't recall it absorbing any hits. Used a reflect seed once but it only reflected my own homing-seed-explosion away from me.
Still a very fun game!!! Gonna feel good the rest of the day, probably. Video games, eh.