But I am not agree .I think relevancy is important in link building work.This kind of link ll give you advantage for short period of time.If you want to maintain high ranking for your website for long term then you need to create backlinks on relevant websites.
You need to be very careful for choosing this type of options.You first need to know what method they are using.If they are using the Black Hat or Gray Hat SEO techniques, then you may have to pay later.
Inbound links or back links are very useful for better seo ranking. They increase the visits from various domains. But backlinks to a website should come from the other websites which are related to their keywords.
Paid backlinks are benifical but the links should come from the same industry websites.