It's not easy to choose a shopping cart platform. There are lots of free and paid solutions. As for CS-Cart Professional, it has lots of features you may ever need, SEO friendly links, one page checkout, unlimited number of products, promotions, even live chart addon and many more. You pay once and use it forever, no hidden fees. CS-Cart also has a free version (CS-Cart Community but it's limited in features compared to CS-Cart Professional).
Magento may seem too complex to you and I would recommend it for a very big business. Try Zen Cart demo, this platform is free and rather popular, it doesn't have so many features as CS-Cart but probably it will work for you. Anyway, I vote for CS-Cart ) Our company is a CS-Cart reseller, we work a long with this platform and on this platform and absolutely happy about it.