We see a lot of deals on jump-starting battery packs, but this $27 model from Aukey is one of the least expensive to date. At 400A, it’s only really designed for engines sized 2L or smaller, but that should cover most sedans and even some smaller SUVs, not to mention things like lawnmowers. And of course, it also works as a 6,000mAh USB battery pack for your phone, so worst case scenario, you can at least call AAA for help.