Cart Advice

I have an e-commerce project coming up with an unusual product display:
https://postimage.org/image/3trxurxvn/

The number of different products is very limited; the variations for each product are many.

The sample data I have been provided with has prices that depend on two variations – length and diameter/thickness. These variations are product specific.

The project should include a method of updating individual products via import (csv, etc.) so the client can update the prices for a product’s variations without having to visit each product’s page and edit the variations manually.

The project requires live shipping integration (for rates). UPS is preferred.

I am comfortable with a moderate level of custom programming if necessary to connect these functions/features, but nothing like integrating with UPS or PayPal from scratch. I am adept at working with a pre-built solution, and only ‘ok’ with working from the ground-up.

I have ruled out Shopp – it only supports product-price variations at the category level. WP-eCommerce is also not an option – I have read many bad reviews of this plugin.

– Solution doesn’t have to be free, but would definitely prefer that.
– Solution needs to have PLENTY of developer documentation with it.
– Solution needs to have an extremely active support forum.

If you have gotten this far – any advice for a good solution?
I have been researching for the past couple of days, but everything I have found either supports some aspect but not all aspects of this project or tells me to forget WP and go to Magento or some other CMS more e-commerce focused. Nothing I have found supports the most important feature – the product variation.

Thanks for reading!