Having just read Choices recommendation for grinders and their previous recommendations for espresso machines I would stay clear of anything they recommend ;)
Have a look at this thread:
I lists some machines that might appeal. You will see over and over again a general concensus that a good grinder must also be considered and in many ways more important than the machine. A good grinder can help a cheaper machine deliver good coffee. A poor quality grinder will deilver crap coffee from an expensive machine.
Note that expensive doesnt necessarily mean good when it comes to espresso machines. Im sure others here can help with their experience with machines around the $500 mark. You should also consider 2nd hand. You can land a good 2nd hand Silvia for around that amount.
Edit: I just noticed that thread listly mostly high end machines :-[ Look in the Brewing Equipment - Entry Level