At the quantity the OP might use, buying by the gallon might make more sense - having a look to Amazon, the popular concentrations in gallon+ sizes are 70% and 99.9% (about the same price, $25 USD/gal) - it probably makes more logistical sense to go with 70% here to reduce evaporation and increase usable liquid on these tall, thin objects (so let’s say “sloppy use” of oddly shaped hard to handle glass).
I’ll leave my update at 70% concentration as the more economical choice - I’d presume based on their comment a soak in ZAP ($18 USD/gal) first is needed, then followed by the iso method… so it’s a little expensive no matter what for something they might not care about that much.