Meta Data for e-commerce websites

Hello!

How do you go about creating compelling titles and meta descriptions for e-commerce websites with thousands of products?

I'd like a WP-plugin that allows you to set a fallback logic based on rules.

So for e.g, [Product Name] | Best price online | [Brand Name]. If over 60 characters > [Product Name | [Brand Name].

Is there anything like this out there or how do you go about creating the meta data?