BlogSpot is free, and you need less technical skills to get started,that’s way most of the newbies who starts a blog, prefer to use BlogSpot as their blogging platform.
Why you should buy a custom domain for your blogspot blogs?
Buying a domain name is cheap
Buying a domain name is pretty cheap, you can easily get good domain name ending with .com or .org in between $10-$13. You can buy .com domain name for cheap from Godaddy or any other sites.
Social media sites
BlogSpot being a free platform, is often targeted by spammers, and this is one reason they are less likely to be trusted by people on social media sites. When you use a custom name for your BlogSpot blog, this removes that first impression of a free blog. Do remember, Social media users doesn’t hate BlogSpot but they don’t even love it.
Talking about web promotion, which starts from social media sites to link building, most of the top websites doesn’t like giving a link back to BlogSpot domain. If you will notice WordPress Blogs blogroll, it will be hard to find a BlogSpot domain there.
Seriousness towards blogging
You have been working a lot on your BlogSpot blogs, but without a nice layout, template and domain name, people will not feel that you are very serious about blogging. One simple reason you are not ready to spend few dollars for the thing which you love.
Using your custom domain name, you can use it to brand yourself easily. Use a nice logo, favico and banner to brand yourself. You can look for WordPress like BlogSpot themes to give an entire new look to your BlogSpot blogs.
With custom domain, you will also get facility to use custom domain based Email address, and you can have email address of your domain name. Like: admin[at]yourdomain.
Later on when you plan to migrate your blog to WordPress, custom domain name will ensure that you will not miss out link juice, and your migration will be more search engine friendly.