It was Barbie's clothing that spurred Jeffrey to begin collecting the dolls in 1984. He now owns every Barbie doll made up until 1967.
He had never thought about collecting dolls, he said, until he saw one in the window of a discount store.
"I thought 'I've just got to have that one,'" he recalled. Then, he said, it quickly became "an obsession."
"The clothing was from my era -- they were so well-made, they were made just like a human's clothing -- with the snaps and zippers and ornaments," he said. "It reminded me of some of the clothes my mother wore."
Prochask, who has collected Barbies for 14 years and plans to use her family's spare room to display her current collection of more than 100 dolls, also says she's driven by Barbie couture.
"It's just such quality in the make and design and fabrics. When we were growing up, at that time it was all about the clothes," she said. "It's a wonderful time capsule of the history of women's fashion."
Jeffrey buys newer Barbie dolls in addition to the vintage ones, but he said they are harder to sell.
The pregnant Midge doll, he said, can go up to $400 in value if in mint condition.
"Condition means everything when you're collecting dolls," he added. "Preferably, they want it in the box and the box has to be perfect -- right out of the factory."
Although dolls are worth less than they used to be, Prochask said collectors are still passionate about their hobby.
"I grew up with Barbie and it was a huge deal," said Prochask, who was born in 1959, the same year Mattel introduced Barbie to the market. "Collectors never forget that feeling they have when they pull out that doll that was part of their childhood."