Most people are squeamish about asking what things cost. It's a carry over from the days when high-end restaurants did not publish the prices on their menu. The reason: snob appeal. The implication was "If you have to ask, you probably can't afford it."
Some artists still don't publish prices on their web sites. That's a bad idea. People use the Internet to research. If they don't find that information on your site, the next artist's site they visit with similar work and prices listed could beat you out for the sale. One of my cardinal rules is "Don't make the customer work to buy your work."
Whether you offer your art on line or in person, taking credit cards is a good idea. You may get that spontaneous sale when someone just has to have your art, but doesn't have enough cash with them. You can offer convenient layaway plans with a deposit. And accounting gets a whole lot easier for you and the buyer.
Here is a no-cost 7-page primer (PDF) courtesy of Rebecca Morgan (http://www.rebeccamorgan.com/) on what you should ask and know about prospective payment processors. "This is written for the online dating site industry, but the info is useful (okay, not the part about if you have nudity on your site). At the end is a link to request a spreadsheet of 'alternative' processors (e.g., PayPal) and their answers to key questions you need to know." (I have no connection with the author of the PDF or Rebecca, but the PDF is easy to follow.)
What are you waiting for? ACT now.
Eyes tired? Listen to "Cash In on Spontaneous Art Buys"