I need to build an ecommerce website within a tight budget and schedule. Of course, I have never done that before, so I have googled out what my solutions are and I have concluded that the following were not valid candidates anymore :

1. Magento : Steep learning curve
2. osCommerce : old, bad design, buggy and not user-friendly
3. Zencart, CRE Loaded, CubeCart : based on osCommerce
4. Virtuemart, uberCart, eCart : based on CMS (Joomal, Drupal, WordPress) that is not necessary for my use-case

So I finally narrowed down my choices to these solutions :

1. PrestaShop : easy-to-use, great templating engine (smarty) but many modules are not free buy yet indispensable
2. OpenCart : security issues and not a great support from the main developer. See here and here.

So, as you can see, I am a little bit confused and if you can help me choosing an easy-to-use, lightweight and cheap (not-necessarily free) ecommerce solution, I would really appreciate.

By the way, I am a Java/Grails programmer but I am also familiar with PHP and .NET. (not with Python or Ruby/Rails)

EDIT: It seems that this question is more appropriate for the Webmaster StackExchange site. So please move this question to where it belongs (I cannot do that) instead of downvoting it. BTW, I have found out a question quite similar on SO (http://stackoverflow.com/questions/3315638/php-ecommerce-system-which-one-is-easiest-to-modify) which is quite popular.