Sponsorship can be an option. For example, if you are making a web series in a certain neighborhood you could perhaps shoot a scene at a local coffee shop and highlight the venue in return for a cost. You can make a short one sheeter for what it would cost to have their shop featured in your series. You could also offer to use a particular product in the series. Like if there is a scene that you are drinking or eating something, etc. Look into sponsorship decks for series/ integrated brand sponsorships.