I hadn't looked at the plugin fees I imagine those could add up. Certainly you could create similar template styles with other platforms but you are probably going to have to do some heavy templating work. But if you are not up for a ton of coding, I don't know maybe you can find an existing theme that you like for Magento, Virtuemart, Prestashop, Opencart, or a wordpress cart.
And you wouldn't be saying that because it's the only one you use?
The issue with someone using just the one CMS, whether that be Wordpress, prestashop, or any other one - is that they are then likely to shoehorn in every site into that CMS even if it's not the one best suited to the project. As they say, "best tool for the job", and no one CMS is the best tool for every job.
Hence I'm very wary of anyone calling themselves "prestadesigner", or "wordpressdesigner", or "[cms-name]designer". Are they really going to offer the BEST solution to a potential client, or the one that suits them?
I did the same research many years ago and found Prestashop.., Magento was also considered but from what I had heard about Magento it was quite complicated and heavy on resources. Having now used Prestashop since 2008..., my advice is to go with Opencart or Shopify but these are limited and costly if you have more than 100+ products. Less than 100 products they are the way to go for sure. These days the open source CMS systems like Presta and Magento need a lot of work and modifications out of the box.