Cost can be anything from $100-$1,500+ for a 1,000-1,500-word article, depending on the writer’s years of experience, level of industry expertise, location, etc. “Typical” would maybe float around $300-500 for the non-technical B2B space (Approx $0.30/word).
SEO writers can swing both ways, charging per article or hourly. Many are leaning toward per article as it leads to more pay predictability for all parties involved.
Re: if 3-4 hours is a reasonable estimate, I'd say it depends on the amount of effort you want the writer to put into the piece, and how hands-on you'll be with providing them project specs. For example, if you provide a comprehensive SEO brief + proposed outline with keywords, top-ranking URLs, etc (and you don't expect them to do any more than summarize top SERPs and add a unique brand twist), then sure, it could only take them 3-4 hours to write the article (not including edits). But if they need to coordinate with internal or external SMEs, mine voice of customer insights, or any other more time-intensive task, that time estimate could easily double… or triple.
En fin, sooo many variables to take into account here. 😅