WordPress Dynamic Box Builder

I’m finalising an online shop for food-item gift boxes and need the checkout to price each order by the exact quantities a customer drops into the box. In other words, if someone adds twelve snacks instead of ten, the total must update instantly to reflect those twelve individual prices.

I’m already running WordPress/WooCommerce and am happy to use an off-the-shelf theme or plugin—Product Bundles, Mix and Match, Composite Products, custom JS, you name it—as long as the end result lets shoppers pick precise quantities of each snack and see a live total before they pay.

Because this is a small-scope job, show me in a short, detailed proposal how you would:
• pick or customise the theme/plugin,
• handle the live price calculation, and
• deliver a ready-to-test site within the modest budget I set.

Link to any similar builds you’ve done and outline the steps you’ll take from install to launch. I’ll ignore template bids; only proposals that address these points will be considered.