Best website for starters?

Haha, well that's the problem with Magento. Agencies give you the best value for your money but can be extremely expensive upfront. It does work out in the long term but I would recommend scaling your site gradually. There's no reason why you shouldn't be able to get started with it on a budget and add functionality as you go along.

I've put together stores with very little custom work for as low as $5k using ready to use extensions. That helps keep maintenance costs low. All I need to do (optionally they can do themselves) for major updates is test on a staging environment and then fix whatever issues crop up. Helps save a ton of time and money because there's very little custom work.

Too much customization has the downside of things falling apart with major updates like updating from 2.3.x to 2.4.x where multiple variables change.

As far as the question of achieving the functionality you're after. Use Itoris Dynamic Product Options for Magento 2. That should get the job done quite easily. I've used it in the past and it's capable of doing what you need and much MUCH more.

/r/smallbusiness Thread Parent