There's a huge variability of cost, even within "good". I've spent thousands on business sites, and I've had sites done for under $100. The former came with more support in design decisions, finding graphics, and planning the site layout. The latter got me an excellent execution on a layout I chose, with little customization.
So, as others have said, "It depends." If you aren't sure what you want, go for a generic site at first. Don't spend a ton of money on a highly-customized site until you know what you want it to be (and, most importanly, why). I've seen many people go for the best with no real idea of what they wanted, and they invariably ended up pushing the developers to create a monstrosity that had to be replaced later.
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