A local company saw some of my work, and reached out offering a gig to draw occasional comics for their businesses' email newsletters to advertise new products. Basically single page, multi-panel comic. They asked me to send them a proposal, just a text outline of what the comic would be, how long it will take me to do, and what I want to charge. If the comics are well received, they said there will be much more work coming. I have the usual rates I charge for private commissions, but I feel like because this is in a sense 'marketing' or advertising, and for a successful business, that I should charge more?

I really have no idea, any help is appreciated.