There are VERY few non-manufacturer sponsored "warranties" that offer any real value. I quote warranty because they aren't actual warranties, it's a service agreement/plan. If you can get a manufacturer sponsored plan, those are usually just a step down from the original factory warranty. You won't be able to get that on a 2005 w/80k on it.
If something is offered to you, ask them what IS covered and what IS NOT covered and that should give you a fair idea of if it's any good. Ask them if OEM parts are included. Ask them their policy on seepage vs. a leak... They like to say some seepage is normal (basically if it's not hitting the ground they won't cover it). If it doesn't cover at least water pump leak, radiator, engine seals, transmission and seals, drive line components, suspensions components, power steering rack, starter, all non-wear brake components, oxygen sensors, etc.... I would think its worth next to nothing.
Also, they (aftermarket service plan people) often disagree with the shops on the flag time to do a repair, which leaves the vehicle owner to pick up the rest.