Some local shops may do this, they're hit or miss in my experience however. You could just hop on to Google Maps and look for repair places in your area and give them a call. They should be able to give you an estimate.
The only place to get replacement Dell Video Card for a laptop would be from Dell Directly. If it's outside warranty, they are not cheap. They only way you are going find a 3rd party video card is if some one happens to have another faulty laptop where the video card is still working. Otherwise, you are taking your chances as just about all the laptop spare part places I know have a pay first with no return for wrong item purchased policy.