I know this post is a little late, but... my ant-proof bowl cost $2!
At the dollar store, I bought a big bowl and a little bowl. Filled the big bowl with about an inch of water, and the little bowl was set in the big bowl and filled with food. No ants since I started doing that. Never really had a problem with slugs, so I dunno if it works on them... it's just plain water, with no soap (just in case the cats decide to lick it...)
Now if only I can get the squirrels and birds to stop stealing the food!