You won't need to buy more roses if you learn how to reproduce them.
The easiest way to expand your rose collection is to order new plants from a nursery. But if you want to experiment with asexual propagation, you can dig up and transplant rooted shoots that emerge next to a mother plant, or take cuttings from the plant itself.
1. In late spring or early summer, cut a vigorous cane that has lost its blooms. Take about 6 inches off the top, removing old flower heads. Cut the remaining cane into 6-inch pieces, using sharp-angle cuts. The bottom of each piece should be cut as close as possible to a leaf node (where leaves form), with no more than two leaflets attached to each cutting. Dip the bottom 1 inch of the canes into rooting hormone powder and plant them; or submerge the bottom ends in willow water, allow them to sit overnight, then plant.
2. Place each cutting in a 6-inch peat pot filled with a moist mixture of equal parts sand, perlite, and sterile potting soil. Mist the cutting, place a plastic bag over the pot, and secure the bag in place. Keep cuttings outdoors in a bright spot that's shaded during the hottest part of the day. Water cuttings periodically to keep them moist but not wet. When rooted (generally within a month), transplant the cutting, pot and all, to a permanent spot in the garden. The peat post will deteriorate over time. Willow water is a natural root-promoting solution made by soaking chopped-up willow twigs in a bucket of water overnight.