If people can't do something, and you have the expert skills, you can charge a large amount
I've done many websites for clients and I start my prices at £220 for a full website with content management system, £5 a month for hosting; and every client I'ce had has agreed that this is a reasonable price
In reality, your prices are going to be driven more by your finances than anything else.
Rather than looking at what others charge (which, imo is a bad approach) look at it from a "what do I need to make to live the way I want to". Now, I'm not talking about being a multi-million aire, so consider it this way...
Start with a desired salary, let's say $50,000 / year (which is probably near average for a web developer in the US).
Now, back track into your hourly rate. Consider that you won't be billing 40 hours / week, more typical would be 20 - 30 hours a week. So let's go with 25 billable hours / week.
So, 25 hours / week * 52 weeks / year = 1300 billable hours / year.
50,000 / 1300 ~= $40 / hour.
Now, here in the US, you also have to consider things like the fact that you'll need to pay both ends of Social Security (7.65%) + your own insurance, so add about 4000 to your salary for Social Security taxes, and about 500 / month ($6000 / year) for health insurance and you actually need a salary around $60,000.
$60,000 / 1300 hours ~= 46 / hour.
Of course, where you live, and your lifestyle play a role, and don't forget that you also have to account for business expenses, travel, etc.
In reality, asking $70 - $100+ / hour, although it sounds like a lot, isn't really that much in the grand scheme of things.
I always worry when I see a new programmer sell themselves short for $20 / hour. That's not a liveable wage anywhere in the US or UK, all things considered.
Of course, keep in mind that the 25 hours / week should be an "average" some weeks you'll have more (40+) other weeks you'll have none.