Use an appropriate feeder, and you will save yourself some money. The female of the species lacks the black forehead patch and brilliancy of color of the male.
Dandelions also get their attention.
When not feeding, goldfinches like the cover in the top of a tree, where they will sit and chatter. Few people realize that their brilliant yellow finch from the past summer is the same drab bird perched at their feeder in the winter. One of our most gregarious and easy to attract birds, the goldfinch's preference runs toward small seed, preferably thistle. Goldfinches have little if any habitat requirement.