I had a dash trim kit that I bought of ebay of few years back.
(Check out the gallery in my profile - it was an aluminum kit).
I got a good one - by that I mean it fitted properly.
They are quite thick and have a UV protection clear coat as a top finish to them.
The kit I got had a sticky back to it. It came with some cleaning pads which clean the surfaces before you literally stick the kit on.
I had no issues with it lifting once stuck down - so make sure when you fit it, you get it right first time because it wont come off afterwards (without making a complete mess of things).
I would personally recommended buying from a reputable dealer, shop or even the manufacturer.
(At least then you have some come back if it doesn't fit).
I'm currently looking at getting a kit from
Dash Kit Mall.