There was a time I know when domain names were key places to hold key words, and people used to trade carinsurance.com or buyviagraonline.co.uk because the name had so much value in SEO. I know that value is much reduced now, but is it still significant? I mean if (without giving away my secret business ideas) I wanted to sell say antique tin cans online would it be important to have the domain vintigaebakedbeantins.co.uk and use it (because people will search for those terms) or could I equally well use timswhims.com (which has no search term value at all). I get that it needs to be memorable, good if it matches the actual business name etc. but I am asking SEO specifics.

Get timswhims.com. The domain name has zero SEO value. The advantage of timwhims is it doesn't tie you down to selling antique tins.

ZERO SEO value now? That's how out of date I am! Good to know, and glad I asked.

You could argue a short or easily memorable domain name has some sort of non-SEO value especially if it's used in printed or video media. Something like amazon,com is unforgettable but imagine if they used amazononlinebookshopinc.com instead!

Aside from that relatively few people type domain names nowadays when searching or wanting to get to a particular site. The majority go via a search engine, type in "amazon" and click a link.

Yes memorable, relevant and simple is the way to go I think. 

Talking of amazon for small scale selling online it often seems to be the best option to go through amazon or ebay so your own website is really of secondary importance only. Is there a whole art and science to getting noticed on amazon itself, and getting your products presented there?

Domain names are an important part of any website. They can be used to create a brand, help with SEO, and make a website more recognizable.
It is important to choose a domain name that reflects the focus of your website. For example, if you are running a business website, you may want to choose a domain name that includes your business name. On the other hand, if you are running a blog about gardening, you may want to choose a domain name that includes the word "gardening."

 A domain name is the address of your website. It's the first place people go to find your site, and it can make or break your business. A great domain name is one that tells potential customers exactly what you do and why they should buy from you. Unique brand name or domain name help  is also important because it's how customers will remember you in the future.

It is a crucial component of one's professional or personal brand. Domain names act as online representations of people or businesses and aid with website memory. A web address is a very precious asset that can be just as significant as the website it is linked to.