Dear Project Owner,
Greetings. I'm Wilson from Malaysia.
Personally, I have some experience on dropshiping. To be exact, I have dropshipped from AliExpress before through Oberlo and Shopify. Although, the business didn't go well but I'm sure building one won't be a problem for me.
The bidding price is what I have for you after some research on the cost. My propose is to use Oberlo which interlinked with Aliexpress and shopify, which meet all your requirement. Also, I will be using a theme which I found suits your requirement on the multi level categories and sub categories. And of course, shopify provides you unlimited number of products you have on your site. Lastly, the shoping cart and check out is also fully functional, shipping methods and the price, and the payment methods is dynamic. meaning you can add or change it anytime through shopify admin portal.
That's all for my proposal. Please do chat with me so that I can showcase the theme I found for you.
Looking forward to hear from you.
Thank you.
Best regards,
Wilson Chu W. S.