I have some extensive experience with "chroming" plastic, as i used to chrome piece for models i used to make and sell on commission.
Theres various different techniques you can use, with the most effective and best solution also being the most expensive and difficult to do.
I have had great results with chrome spray paints, however the pieces need to be literally flawless before they are painted and almost never touched again, its purely for show.
Its a long and extensive process too, requiring a flawless black base and various coats of the chrome before you can lacquer it, which also has to be a certain "special" type or else it will just eat away at the shine from the chrome layer.
Even then it isnt the most durable of finishes, and is prone to chipping and scratching very easily and theres no way to "polish" it out, it has to be completely stripped and re-done so not good for something like a car thats always exposed to the elements and some level of wear and tear, especially something like a door handle.
The most expensive but most durable solution is to have them "vacuum metalized", which is basically what you mentioned. The parts are put inside a vacuum, witchcraft happens, and then a chrome coating is what you are left with.
It looks good, but again can be prone to a myriad of flaws such as wavey lines in the chrome etc. I had some plastic pieces professionally done and though they looked great they weren't flawless and they cost a pretty penny to boot.
Ultimately theres no sure fire way to chrome plastic in house without there being potential issues (granted its been a few years since ive done it so there might be new products out that make things easier), and certainly no way to do it at home without things like compressors and air brushes (or if you want to spend a fortune buying one of these vacuums) and a lot of patience.
There are companies that do it based off a quick google search, but its likely to be pretty expensive and is it really worth the cost vs the gains?http://www.vmclimited.co.uk/http://www.apmetalising.co.uk/index.php