I find the Smena (Smegma?) 8 has a rather too good a triplet lens for 'toy camera' pictures. The one trait I found it has in common with the Diana is that is disintegrates in your hands: the plastic's strength is as if the camera had been carved from soap. The Smena Symbol is supposed to be better built.
A cheap disposable camera would be the common 'toy' 35mm. Buy the crapiest you can, some of the Kodaks have actual 2-element achromats for lenses, so watch out for lurking quality.
They also make cheap 35mm reloadable cameras in the US: "Barbie Cam", "French Fry Cams", etc., Dead Link Removed for more info.
I would go to a toy store to look for them. Here they also show up at thrift stores run by charitable organizations, I don't know if these stores exist in Greece.