is it rquired to be in joomla or as a external site external one's are better in my eye's something like os commerce simple ish and does what you need and lots of feature's ( when i mean external not built into joomla but built into the website still )
os commerce really could do with 50 + products if for photos then look at neil's post
the other way of doing it is to use pay pal as the card hosting if you go to paypal there is a section where it can produce code to add a product so it has a buy now button it then takes you to pay pal where you can pay by pay pal or credit card / debit card and for this you do not have to have a pay pal account
please note something like os commerce will need regular updates for security reasons so can be a pain to remember
the good thing with pay pal but it now you can add the product on a page where ever you like past the code in and jobs done if you need to remove the product you just remove the coding and the product if you want to add it is simple to add aswell
the only html knowledge you will need is to turn the page from text to html which there is normally a tab and then knowing where to place the html code correctly from pay pal site which is automated code by them