how much to setup online e-commerce website?

If this is your product first entry to the market, try out apps like carousell etc first. You can even try out with facebook page and use a third party vendor for payment gateway (e.g. paypal)

Get a guide on the market response before launching a website.
You can use a hosting server such as bluehost to launch your own website etc, if you are able to design your own website, the cost will be low (less than 300 usd) to set it up.

Alternatively, you can also use Amazon as a platform

I'd recommend first testing the market with Carousell or Shopee first?

I've seen many interesting businesses which start there.

I feel that building up a website from scratch may need more time and effort and money, which should be the next step after validating the market first :)

If you are keen, then you can use either:

• Strikingly
• Wix