Marketing a product without UL Listing?

In the next few months, I’m looking to bring a bit of electrical test gear to market. It’s a very niche market, and I expect to sell no more than 50 of these to a specific industry.

One portion of the gear connects to high voltage (120v) circuits to test them. It will be fused, but due to the small market I won’t be able to afford UL (or other NRTL) testing.

I’m planning to purchase liability insurance to cover this (and discuss the issue with my agent), but are there issues with marketing a non-UL product in the US?