If you need a shopping cart to integrate into a website so it looks like it’s part of the site but can’t afford a team of coders, I would recommend you look at e-junkie.
It has a great user experience (they never leave your page, no pop-ups) together with very simple cut and paste integration, without ruining your site. It is especially set up for digital downloads, but includes sophisticated control for physical shipment too. No coders required. At all.
This isn’t the only option you have in this space, so you’ll need to think about your particular circumstances, capabilities and capacity, but if you are researching cart solutions, add e-junkie as your baseline comparison.
There’s a free 7 day trial, a first test cart would be up and running in a few minutes.