As other have said, nice website! Really well presented and nice see one not riddled with spelling mistakes.
Our local German specialist does solely AT but I know others do really well off FB and with your tech skills i'm sure you could build a bit of a brand on there.
Ditch the sportswear for the video (you did ask for opinions). No one wants a shiny suit these days but someone in a footie shirt is almost as off putting as buying a car from a Midlands postcode from a guy with a tracksuit and one of those stupid Eastern Euro bags they all wear. Just an opinion though.
Nick makes a really good point about the lower price point. You probably know more about German metal than me already but you will make mistakes, it's inevitable in this game and it's better to cock up on a 5K lump than a 15K one.
Also, unless you're doing it for a bit of fun, just remember the fundamentals. I don't mean to sound like a d**k but so many new traders forget. If you earn 1K clear out of a sexy 15K 3 Series and £800 clear out of an ugly 5K 1 Series then you want to be stocking three boring one series not one shiny 3 series. If you only want to stock the sexy stuff then it's a hobby/vanity project not a business.
The forum is a wealth of knowledge, must be an answer to almost every question, so worth reading through a lot of the old posts.
Finally, best of luck!