Walmart - $13 dollar 10Gal Fish Tank
Ants - Free
Fluon - ....$35 dollars to keep them contained. I've been told its "The worry free barrier" IF YOU REMEMBER TO reapply when needed.
I'm doing the same set up and have put on the glass, under the lip, and on top of the tip and I'm still freaking out some. - on my first night I woke up periodically to check on things. This is supposedly extreme overkill as a little goes a long way and does a fantastic job. I probably won't be fully satisfied or comfortable until I build a halo ring that will extend the fluon barrier or use some 100 micro meshed screen.
Something that hasn't been addressed is people making their own fluon. Small side project that I'm trying to look into. Considering its just PTFE-30 + water in a 5:1 ratio..... Polytetrafluoroethylene at least. I ended up buying premade byformica product the first time. I'll most likely utilize my degree for the second round because I'll probably run out before I should.
To address the silicon at the top, simply cut a small chunk of the silicon out (keepint it sill connected on the outside wall) but removing from the inside to expose the glass. Apply fluon to the glass as the silicon isn't smooth enough for effect. I'd think that the tape (if smooth enough) would work though.