You don't have to buy things to worship if you don't need to.
The first step that I would do, would be to research the mythology behind which Greek God/desses you're attracted to, or feel drawn to, and then start researching different ways to go about following Them (because the word "worship" has always thrown me off). If you learn about Them, then you'll know a better way of approaching Them in the right way. There are websites that give out mythology about the Greeks, such as theoi.com, as well as books such as Mythology by Edith Hamilton.
If you ever need help or advice on how to start down the Hellene-ish path, I'd be more than happy to help you. I've been at it for quite some time now.