E-Commerce Site revamp needed

I have an e-commerce website that is currently live. This website has been online for a while and i have not started marketing it as i dont feel it is perfect yet. I need the website to be to attract customers, make purchasing of products simple and have a streamless re-order process so that sales can continue automatically. The site is currently developed in JOOMLA! but i am open to any platform/code. I have also spent enough money on this site and dont want to have to pay large sums to get this redone. I dont mind using the current platform JOOMLA! or redeveloping on a new platform, but cost is my major issue on this project. The site intends to move everyday essential items to businesses. I would also like the site to be visible on all search engines and hopefully be able to generate a few hits from searches. I will be employing an seo agent once the site starts making money. In brief, here are some items i would like to add. It would be a huge plus if the successful bidder could also add his/her ideas and extra concepts which could make this site really work: - Easier Shopping interface - Streamless ordering and possible payment through site (although not essential) - Customer order history. Easy to re-order same stock as well as add more products to their stock - Items Specials on display. Can also be replaced with something should we not have any specials at the moment - Email reminders for customers to order again. There are consumable items and need to be ordered on a regular basis There is currently a login problem that needs to be sorted as well. Does not seem to be a major issue though. I try login and on the odd occasion, it says login expired. other times it logs in easily. This is the general stuff i need. The framework has already been provided, the site is live. If you can possibly offer me great service at an exceptional rate, i will have extra work in future. Thanks