I used a thick screwdriver and a hammer to get the screwdriver up under the lip of the lid. I cursed that lid every time I tried to get it off. I just invested in a lid opener, I haven't tried it yet. Hope it works better than the screwdriver.
They care them in the paint department at Home Depot, too. Around 5-10 dollars, but I'm thinking it was cheaper. I almost picked one up the other day for the paint buckets, they kill my fingers!
I used to work in a deli and we had pickle buckets like that. If you put 1 knee on the middle of the lid and put your weight on it, the lid comes off alot easier.
Use a carpet knife and a mallet or hammer to slice down through the slits. Stick the knife through then tap it downward to slice. Then use a bucket wrench to pry it off.
If you don't do the slits (which may look like indentations) it'll be a bear to get off.