Help creating a custom search for website

Hi everyone

I’ve come across a problem and I was hoping someone here might be able to recommend a solution.

I need to create a custom search for a website and I need the search to look for results from multiple domains.

Eg. Someone searches for “Keyboard” and search function returns results from many different domains where the keyword “Keyboard” was found. Of course, I want to specify the list of domains to search.

My problem is that most of the options I am finding have hard limits on the number of domains I can search through.

I’ve already created all this for free using Google CSE - but when domains increased over 100, I found that 100 is the limit. After 100, domains, the search results get messed up.

I then created this again using a paid subscription for Bing Custom Search API but again.. Once my number of domains requirement exceeded 400 - I found that there’s a hard limit of 400 domains.

If someone could suggest any other cost effective methods on how to get this done, I would really appreciate it! Thanks