What are the best and most cost effective sites to find business partners?

Gavin - start with LinkedIn - I have made some tremendous connections there that have paid great benefits.

As well, you may want to search Zoominfo, where you can find people who are in specific roles that you seek to connect with.

Yes, thanks Ed. I have Resolved this with approaching Business units aligned to our core product. However This was easy in my home country. Now what is the most effective way of reaching the same or similar on ...say the USA or Canadian market?

There is a website and actual business that makes a business out of liking founders -
https://cofounderslab.com/

There are two levels, free and premium. You can post your brief and search for the skill sets you seek in the other person(s) you need for your team,