Are some digital marketing companies meant to help small businesses?

We work as a partner to Startups as Digital Marketing Company Ahmedabad India, SEO, SEM, Social media Marketing
As startups have more need of funding and very low budget for marketing, and startups always need more marketing as they have best of product or services in their field but very few people know them that they exist.
It is very difficult to charge them what we charge others due to funding requirements, so it is best suited to work with them as per their requirement of marketing in very limited budget, and reinvestment of revenue again in their business.