build a wordpress plugin

I want to build a small plugin for now (which will be developed further) to show buy now buttons inside a widget. There are very few things which i need to be done right now : 1) Admin panel page to build a widget 2) Add different number of products 3) choose a product image to be shown and price with each product 4) Change CSS and other details like buy now button 5) use shortcode in widget or post/page to show the product. Please note i will need a way to keep updating it (you will be paid to create updates too so remember that) Let me know how much you will charge for this. Please keep in mind that this should not take more than 20 hr.s of work. So price accordingly. I have 10 plugins on extend in WP and i got them all built from freelancers. The winner will get to work for atleast 8-10 minor updates on this and build other plugins too.