Never get link building services from Fiverr or ultra-cheap freelancers. I've seen some freelancers doing link building for something like $5/hour. An average (experienced!) SEO marketer would cost about $18/hour minimum.
The only thing you should expect from Fiverr or ultra-cheap link building services is a penalty.
Also, always use known SEOers or established agencies. Check their reviews, check their portfolio, CAREFULLY check and review their application/pitch. Nobody can guarantee a position in search results. Nobody can guarantee a certain number or percentage of visits. Always be careful of any kind of guarantees. There can't be many guarantees in SEO. The algorithms are always changing and updating (even in real-time, through machine-learning algorithms) so there can't be any guarantees.
Like you said, there's been an influx of SEO "gurus/ninjas/experts/masters" lately, and they are all, to be frank, shit. Some of them (mostly from Asia) don't even speak/write proper English. How can you expect a good SEO campaign from someone that doesn't even know English?
The problem is that a random business owner doesn't know much about SEO, and can easily make the mistake of hiring an inexperienced person.
My team can do organic, white-hat, quality link-building services, but we aren't cheap
Which services in particular are you looking at?