This is what you'll need:
- piece of ribbon, about 30 cm
- needle and thread
- piece of steel/copper wire, about 20-25 cm
I used a fairly thick wire, because that's what I had lying around. The rose is not that heavy, but you do want the stem to have at least some thickness, so I wouldn't use too small a gauge.
This is some kind of rubbery stretchy green tape, you can probably get it at any florist. You need about 30 cm per rose.
- somewhere to work where you can spill glue
The only things I bought for the roses were the florist's tape and the ribbon. I can't remember exact prices, but I think it came out to about one or two euro per rose, so not that expensive.