A reversing ring is probably the cheapest way to go without buying lens. The ring has to match your camera system and cost less than $40. Mine for the Nikon is 52mm diameter so if the lens you want to use with it is different you will have to get a step down ring to fit. They are only about $12. The nice thing is you can use any lens you can find that has the same filter diameter. You might find a really good piece of glass in a flea market for an older film camera. It will work with the reverse ring just fine. Keep in mind everything has to be done manually.