This is so simple, I don’t know why I didn’t think of it before.  You can make a decent blog search engine, for free, in minutes with Duckduckgo.

1. Go to the Duckduckgo Search Box page.
2. Do whatever customization you like.
3. In the field “Site Search” type in: blogspot.com,wordpress.com,medium.com

Medium.com is optional.  Copy the searchbox code and Paste it on an HTML page and you are done.

Pros:

• Because it’s DDG all searches are private.
• Blogspot and Wordpress are the two largest blog hosts on the web, at least in the Western World.
• Fast results with very few ads.
• DDG does not insist on having their branding all over the searchbox.
• You can do multi word, complex search queries.

Cons:

You are not searching for all blogs. Only blogs hosted on a subdomain “blogname.blogspot.com” are going to be searched.  Blogs on these same hosts that pay to use their own domain will be overlooked.  Also, blogs that are self hosted on their own servers will be overlooked.

Have fun. Adapt this to your own needs.  If you find this useful on your own site, come back and let me know how you use it.  Thanks.