Product Add on & Dynamic Pricing

I need a plugin that can offer extra product options (add ons) that can use conditional logic and fixed pricing.

I also need a ‘compatible’ plugin that can offer pricing rules based on quantity. For example 30 @ ￡2.25 each, 40 @ 2.20 each, 50 @ 2.10 each and so on.

The main thing here is that on the product page you need to be able to see the price change on the fly, depending on the quantity selected and also change with the options selected.

Do you have anything close?