I installed zen cart but it does not seem to be exactly what I am looking for because of the way shipping is calculated. My site will have at least 500 different items. I am looking for something that will allow me to say shipping is $x if purchase by itself or $x-y if purchased with another item. Basically, custom combined shipping. For instance widget01 is $5 to ship plus $2 for each additional. So a quantity of 2 widget01 would cost $7 to ship. widget02 is $3 to ship plus $2 for each additional. So 2 widget02 would cost $5 to ship. Now if a buyer was interested in 2 of widget01 and 1 of widget02 then ideally the shipping would be $9, not $10. Is there a shopping cart out there that would allow something like that without needing heavy customization?
It is hard to say definitely which CMS is the best To my personal opinion Virtuemart and Zencart are the best choice, as they are the most convenient and easy in usage, their fetures list also is a little bit better than the rest ones have