I guess if you add more durable items to the list like Carhartt gear and have equipment like a backhoes that would add more perspective to Lee's point, but the real expense is much more hidden then that. A great logo design is not arrived at easily. Well, sometimes it is, but even if the right idea strikes in 5 minutes I would still fully explore the options to be sure since a logo is more important and requires more planning than most people realize.
A logo is much more than just a cool graphic that the owner likes. When you figure the mileage you get from a logo, doing it more than once is very expensive. And not putting enough planning into it the first time is expensive too, but that expense is only realized by people who get educated and/or think it through logically. Once created, you want the market to recognize it and associate it with your business.
Although it's technically only your visual representation, everything you do in business builds your "brand" whether you choose to carefully create that brand in the minds of target customers or let it happen by default. Either way a brand will be built. The idea that branding is just for big business is a detrimental misunderstanding of what branding is.
By changing a logo you must now start over with a recognition symbol. It's not just the money to "relabel" everything, it's the process of getting your market to recognize the logo and associate it with your business. That is definitely expensive.