Becoming a player in the rarefied world of art sales had never seemed easier. Without moving from their armchairs, viewers of the cable TV show Fine Arts Treasures Gallery could become the owners of works by some of the greatest artists of the 20th century. Picasso, Chagall, Dalí all came up regularly on the show, often at surprisingly low prices.

But when the winning bidders received their authenticated artwork in the post, they realised that something was not right. Often the expensive artworks were sent uninsured by the dealers. Some of them arrived bent out of shape or with staples through them. Others appeared to be expensive photocopies, executed on ordinary copy paper. And while many of the artworks were signed, as promised by the auctioneers, they were not signed by the artists.

This week the Los Angeles area couple behind the scam were charged with conspiracy to commit fraud in a scheme that prosecutors say saw them take more than $20m (£10m) from 10,000 aspiring collectors.

"I bought an 'original lithograph' by Pablo Picasso, according to the auctioneer," one of the TV auction's customers wrote on a consumer rights website.

"In actuality, I bought a cheap copy of an original lithograph by Picasso that is not worth anywhere near the $50,000 they said it was worth - nor is it worth the $5,000 I paid for it. In actuality, it's a nicely framed and matted piece of trash worth about as much as the frame and matting."

Describing the scheme as "just like shooting fish in a barrel," the collector concluded: "I regret ever having trusted a word that emanated from any of their crooked mouths."

The couple behind the scheme, Kristine Eubanks and Gerald Sullivan, are cooperating with the investigation, and face a maximum of 10 and six years in prison respectively.

The couple told investigators that they inflated the bids on their auctions, purchased fake art, forged art on a sophisticated printer and sold the works on their television show and internet site.

Investigators from the FBI seized $4m and around 1,000 pieces of art in a raid last September, but attempts by defrauded clients to get their money back could be protracted. Sullivan filed for bankruptcy last week.