Moving a old blogger blog to custom domain

It is always a good idea to start a fresh blog if you are buying domain name. The reason being migrating subdomain blogs from blogger will have the loss in traffic due to permalinks change. Also if the blogger blog remains idle for long, the content from the blogs end up not getting much traffic. So you have to start fresh in such case.

SEO & Permalinks If we try to look at this from the SEO perspective, you have to do assessment of the current content. You have to find out the traffic and the search placement of the current content. If you are getting good traffic for the current set of keywords in your headline and the content inside, then I'd suggest sticking with the blog.

Drop in Traffic If you're losing the traffic consistently then start a fresh blog and then assign the new domain name for that blog. Make sure that this time you host the blog on WordPress or any other CMS. As that move from the start of the blog would save you a lot of money later as SEO permalinks migration may cost a drop in traffic. Also monetizing on subdomain of blogger has it's limitations.

Note: If your blog has traffic and has some converting pages, I'd say keep it as is and don't delete the domain. Just start new blog with new domain name (or subdomain) and start over with your new content strategy.

I think this whole issue from a psychological perspective. Just see, even when you were getting enough traffic to your old blog, you left it. This shows that, you were not getting motivation enough with the same old thing.
So, unless you are re-motivated with the same old stuff, there's no point in trying to repair the damaged.
This way, you can enter to the earlier loop and again lose out in traffic and thus your interest.

A custom domain will give you a fresh start, there, as you invest money once, you would feel like working positively towards the blog.
There to make it content rich, you may or may not choose to borrow the contents from your earlier blog, but certainly you would be motivated to get new and fresh content to it everyday.

So from every angle it makes sense to go for a custom domain, and I would suggest from my side, to give it a broader name that can include more topics and subject matter, even if it is on one particular niche.

I feel moving your older blog into new custom domain would be a better idea. Your older blog gave you good feedback by showing 500 to 1000 views per day. But unfortunately you have left it for a while. This impact will reflect through decrease in views. This shows the interest level of the viewers might have reduced. Modification in your old stuff doesn't create a good impact at present. So creating a new custom domain with your full activity brings back everything.

You can move your old blog to new custom domain by the following:
1. First you have to register your new custom domain.
2. With the help of DNS address, setup your new domain.
3. Make a stabilized time for your new domain.
4. Click X.
5. Next, publish the blog in BlogSpot.
6. Then change the BlogSpot URL.
7. Publish this blog to new domain.
8. Once cross check this blog for any issues.
9. Get redirect your old blog to the new blog.
10. Finally publish your new blog.