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Basically the story goes, im going to hopefully live in america as a student for a couple of years next year, I've gone on holidays there quite a lot and I know that without a car you're pretty much just F*^£ed over there.

So I think I went on to a site like autotrader like we have in the UK but the american equivalent( New Cars, Used Cars - Find Cars at AutoTrader.com) and started to look at cars, I soon found out that cars in america are really expensive to buy. I didn't know what kind of budget I would need for a car, so I started to look at how much my car would cost in america( BMW 325i saloon/ sedan 2002 quite low mileage)
the price was something ridiculous like $13K. Plus the cheapest BMW started at 10K and those cars were a piece of *** if I tried to sell my car in the UK I wouldn't get over £2K for it and I would be lucky to get £1800. So then I started looking at Audi A3s since my friend had recently bought one for £3K( pretty decent 2005 quite low mileage, all the bells and whistles you'd expect from audi) in the UK, again I looked at that site the equivalent nearing $16K and the cheapest one on offer was for $12.5K, ITS LIKE WTF, so then I thought it might be becuase its a german cars in america and the price of the import.
so I looked at Ford's since they are made over there, same story a piece of *** Ford I think that wouldn't go for £1K over here is costing near to $7k.

I need a couple of things answered:

1. WHY????
2. Does it matter what state you're in( Denver)
3. What would you recommend for a student with lets say $4K budget, what would be the best second hand car.
4. what makes are the best with a low budget in the US.

Thanks in advance for the help and advice!