John Valuk

I went through a similar decision-making process a while back. I went with Cinelli cork gel, in black (~$18).

That let me get some experience without much anxiety over possibly botching the job with more expensive materials. I'm satisfied with the results, and I can use this as a baseline when deciding which way I might want to go in the future (more or less cushy, grippy, etc.).

Drakonchik

Self-adhesive silicone tape. Makes all the bike shop bar tape obsolete ( though still useful as a base-layer.)

I use the brand called "RESCUE TAPE" but there are several others.

About half the cost per cm as average bar tape. Comes in lengths more than sufficient for laying on a complete second layer.

Way, way more versatile and permanent for covering unusual shapes and attachment points.

Bigbus

I carry a roll of that stuff in my truck for emergencies. It will literally fuse a water tight seal on a busted radiator hose (ask me how I know) It's good stuff. Never thought of using it for bar tape, but you're right, it's a whole lot cheaper by the inch.