Basic E-commerce website

We need someone to develop a new e-commerce website based on an existing site. The website should be SEO and mobile friendly and have a modern UI. The site will be a Will writing service therefore requires online form filling which is linked to payment options.

The site should be tested across all browsers and support secure payments with Paypal (and credit cards, debit cards if needed)
Candidates should have a strong attention to detail, background in e-commerce platforms and experience building online stores.

We would need to see previous examples before commissioning.

Thanks