The women were testifying at a pre-sentencing hearing for Vitaly Borker Wednesday, the New York Post reported.
Borker pleaded guilty last year to making threats and fraud, but has denied threatening to rape or kill anyone.
The women said they were threatened by Borker after they complained about getting ripped off by his DecorMyEyes.com Web site.
Clarabelle Rodriguez, of Manhattan, testified Borker threatened to sodomize her after she questioned a $486 charge for a pair of apparently counterfeit Lafont glasses.
"I was appalled," she testified. "I've never been spoke to like that by anyone. I was in shock. I started to cry and hung up."
Melissa Kross, of Chicago, said Borker repeatedly called her during a dispute over a $200 pair of Dolce and Gabbana sunglasses that she never received.
"He said he'll beat the crap out of me," Kross testified. "At one point, he actually threatened to kill me."
The judge in the case said the testimonies were "highly credible" and had Borker jailed.
Borker will be sentenced at a later date.