A few thoughts,
One step would be contacting UL, or any other testing/certification agency to determine the costs to have this equipment certified.
As Greg mentioned, check the equipment for any labels/listings.
After determining the cost to have it certified, compare with cost to replace.
A recent UL field cert for equipment here was about $20k when all was said and done. This client was aware that the equipment was NOT UL when it was purchased, and was not too concerned of the cost.
