I think as long as it's something the provider needs and is willing to barter for that's fine. For instance my side hobby (aside from this hobby) is that I get old "dead" laptops and refurbish/repair them. As a result at any given point in time I will have a stack of low to mid range laptops around my house. These aren't top end machine, but great if you just need something to hop on the net, browse the web, post
respond here or check your P411 account from while at an incall.
I know a provider who mentioned in chat one day that she really needed a provider-specific laptop so she didn't have to worry about prying eyes on her normal computer. As a result I traded her one for a very nice session. (These are laptops that if I sell them on CL I get around the same price for as a nice 1hr msog session)
That worked out well for me.
I also know providers who even openly list that they will do appointments for non-cash commodities and don't see a problem with it. Money is simply a medium for when you don't have specific matching needs for a barter