Wix website bespoke features build

Hi, I have a wix website and have set up the basics and am reasonably happy with the look and feel of the site. I would like someone to build a few pieces of additional functionality on the website. 1) I want the ability for my customers to submit a price they can choose and are prepared to pay for an item on the cart/checkout page. I need to have the back end capability to easily see the item they want, the customer bid price, and I want their cart to remain active whilst I decide if the price is acceptable. If it is, I wish to press a button which sets the sale price to the one they entered or I have the option to alter the price to my choice. 2) I have a filter menu on the shop page located on the left of the screen. It works well but I would like this as a drop-down menu, similar to the menu already across the header area. I'd like the drop-down menu to be present whenever you see the header section. I'd also like the drop-down to show all items even if the customer is on the home page showing the highlighted products view. Basically, the ability at any time to filter all the products to the choices in the drop-down menu. Like shoes, bags, clothes etc. The website is [login to view URL] If you respond please tell me what similar work you have completed in wix and send a link to the example of your work. I need this built in the next 10 days. Many thanks