Health & Fitness Clubs selling gym memberships, CPR courses, weight management class, yoga or kickboxing, etc. should imagine the revenue from just ten extra people! Of course, you have to pay your staff and other expenses related to the running of your business, but the truth of the matter is that those are fixed costs you will have regardless of a few extra barter customers! You are trading space.
Earning full value for space or seats that would otherwise go unfilled, is found revenue! This additional revenue can open up an advertising budget or offset some other business related expenses for you like commercial cleaning, or computer repair. Why pay cash for things you need when you can trade your time and space?