The domain I want for my business is taken and I don't have the $$$$ to pay the asking price. So it's either I settle for a .co or add "the" or "book" at the front of the name in the domain (ex: thesoulretreats or booksoulretreats) but only use Soul Retreats in branding and marketing campaigns that will embody the brand. Which is better for brand recognition and seo? To just go with .co or add book/the?
The domain name plays a big role in SEO ranking, however it is not the only relevant factor. If you have a state of the art website (polished content, good site map, etc) you can minimize the effects of having not the ideal domain name.
To take the best decision you need to check whether you have other companies with similar brand name , that can be easily misled with your company name.
In general I would go for .co so to ensure a consistent brand identity across channels.
Hope this helps,