Paying for a guest blog post with a Domain Authority (DA) of 50 can be worth it for SEO, but it depends on several factors and your overall SEO strategy. Here are some considerations to help you make an informed decision:

Relevance: The most important factor is the relevance of the guest blog post to your website's niche or industry. The content should align with your target audience's interests and needs. A DA 50 blog in a related niche is likely to provide more valuable backlinks and traffic than a high-DA blog in an unrelated field.

Quality of Content: The quality of the guest blog post matters for both readers and search engines. High-quality, informative, and well-written content is more likely to attract and retain readers. It's also more likely to pass on valuable link authority to your site.

Natural Link Building: Google values natural link building, so the links in the guest post should be contextually relevant and not look forced. Avoid over-optimized anchor text and focus on creating valuable content that naturally includes links to your site.

No-Follow vs. Do-Follow: Check whether the guest blog offers do-follow or no-follow links. Do-follow links pass on link authority to your site, while no-follow links do not. While do-follow links are more valuable for SEO, a mix of both can appear more natural.

Website's Reputation: Assess the guest blog's reputation and history. A site with a high DA may not be beneficial if it has a history of spammy content or is associated with questionable SEO practices.

Cost vs. Benefit: Consider the cost of the guest blog post and weigh it against the potential benefits. If the cost is reasonable and the blog offers a good opportunity for exposure and backlinks, it may be worth the investment.

Long-Term Strategy: Think about your long-term SEO strategy. Building a diverse backlink profile from authoritative sources is essential. One high-DA guest post might be a valuable part of your strategy, but it should be one piece of a larger plan.

Monitor Results: After publishing the guest post, monitor its impact on your website's SEO performance. Use tools like Google Analytics and Google Search Console to track changes in traffic, rankings, and backlinks.

In summary, paying for a guest blog post with a DA 50 can be worth it for SEO if it aligns with your niche, offers high-quality content, provides natural and relevant links, and fits into your broader SEO strategy. However, it's crucial to do your due diligence, track results, and make data-driven decisions based on the actual impact it has on your website's performance. If you wish to have this service, Aasan is a company which is doing a similar work and will provide you high quality Guest Posting Services.