BigCommerce 2 Magento Move

I currently have my website online at [login to view URL] (Big Commerce) But I'm thinking of moving it to Magento, as it's free and I can add plug ins. I'm looking for an idea of cost and timescale on this. Please don't take this on if you have other commitments, as due to past experience with people not delivering, I will be quite forward. The main work is done, the HTML is coded, image sliced etc. Just needs moving over, I've got about 50-60 products I want to move across and keep same URLs, but I presume that can just be exported/imported? It doesn't have to be an exact match of the current, but I want to keep the header and side items in place, maybe add some extra buttons to top "my account etc" - so an existing theme could be edited to fit, header dropped in etc. Let me know an idea of price and timescale and I'll get back to you. Not looking to spend a massive amount on this (under $100, lower the better), but if it saves me time it's worth while!