trasnponder keys

Using a database won't tell you if the key has a chip in it or not.

For example. 2002 Nissan sentra, everyone on the forum said it had an immobilizer that needs to be bypassed, every wiring guide (bypasskit.com, autostart, directed electronics, and astrochart all say it has an immobilzer, it doesn't however. )

There are a lot of vehicles like this, normally the cheaper model in the line up, the one that doesnt have power locks or has a manual trans.

This is much easier then telling them it probably doesn't and then slapping it on the bill at the end, you may loose a customer or 2 if you tell them the high price even though it doesn't require a bypasskit.