I wouldn't go too cheap on this.

Consider that this is a tool that you're trusting to get you out of a real big jam.
Maybe on the side of the road, in the dark, in the rain, miles from nowhere?
Maybe you won't be there(or you're injured) and your significant other will have to use the kit?

The really cheap kit's have poor handles that can break and/or junky probes and needles that can bend or break. I've experienced this myself.

I agree that the cement should be used liberaly and probably replaced every few years
if your kits live in a hot trunk.

The Black Jack kits are a good bare minimum.
I bought a box of 30 plugs and two each of the plastic handled probes and needles and split the plugs between two cars. They take up very little space in my car kit.

I'm set and I trust to tools.