I'm of the belief that no one should ever start a business without a sufficient level of start up capital on hand to do it. It's poor planning to go about it any other way.
Just as you want to have at least a few months of content on hand before launching a content site.
Just as you want to have your servers and hosting issues geared up and ready to go.
Just as you should want to have established traffic sources/trade relationships/business relationships set up before launch.
It's just the wise way to go about starting up a business - adult sites included.
If you can't afford the Visa fee right now? It's not a guaranteed "right" to launch a website how and whenever you want and expect it to be successful. Hold off until you do have the capital. Acquire a partner who can foot the bill. Something.

I saw enough mainstream companies go under during the dotcom bubble-burst on account of not having a thought out business model and capital base to keep themselves up and running through difficult periods. That squandered and wasted the money they made during healthy periods only to find themselves broke and hopeless during difficult periods to the point of having to close shop.

I'm all for the Visa fees as they are right now. Why? Because as a legitimate webmaster I have absolutely no problem with efforts to legitimize others. As Craig said, no one has to look very far to find webmasters who operate with shady and shifty tactics. Screwing consumers and the rest of us with the way they run their "businesses". Any reasonable step to weed those out and keep the rest of us secure is fine by me.

For the people out there running illegitimate businesses designed to fuck over customers, something like a Visa fee is a punitive step. For those of us on the up and up, it's just a regular old start up/operating cost.

My 2cents.