I tend to work on the following scale;
£5,000 - £8,000 advertised price should yield £1,000 profit.
£8,000 - £15,000 should yield up to £3,000
£15,000 - £33,000 should yield £4,000
Then it increases as vehicle value does until you get to £100,000+ where it can be circa £15,000 profit. But, vehicles priced at £100,000 plus need regular, precise maintenance. It would be typical to spend £5,000 conseratively on a vehicle being sold at those prices.
It all depends on what you expect from a vehicle, and if choosing a dealer, what you expect from them. You are paying them for their knowledge and the security they will look after you, that is sometimes what frustrates me with main dealers. Some 'sales executives' know nothing about cars, they're just annoying pushy people. I'm no mechanical expert, but I only pick cars I like/enjoy/have enthusiasm for...as it makes my life much easier. It's all about a good stable relationship with your customer, and a respect.
I wouldn't see it as screwing, it's just how money is made. One wouldn't expect a builder, hotel, office manager to work for free.
For example, this year my insurance is circa £4,300...on top of that is the public liability insurance, trade plates, limited staff I use occasionally, tax, advertising, non payment from account customers etc.
Some car dealers I know; I despise. They're stupid people, who cut corners, and sell utter crap. I wouldn't buy a newspaper from them!
I do other things besides sell vehicles, which keeps me sane - it's not something I would want to do all of the time.