transponder keys:
this statement "Transponder chip keys – these types of keys must be coded on site with a special machine, otherwise the car wont start. These are more expensive to make"
is to encompasing of a blanket statement. Many transponder keys do NOT require on site coding with special machines. An example is many GM keys. You order the key by VIN number, after showing proof of ownership. When you get the keys if you have TWO working keys, you can easily program them yourself in the car including such things as the "valet" or "teenager" mode restrictions. If you don't have two working keys, then it is more complex and a locksmith or dealer needs to program them.
GM transponder keys in 2016 were around $40 each, Fobs more expensive of course.
More and more mfg are requiring proof of ownership to get replacement or spare keys. Recent interaction with GM, MB, and Acura dealerships, they require registration showing proof of ownership, valid ID matching, take your picture, have you sign documents before they are allowed to even order a replacement key or fob. In some cases they require the vehicle to also be present.