I love hand-painted roses! I see you already have four on your want list (Champagne Cocktail, Hope and Joy, Incantation, and Regensberg). These are great choices, but Regensberg is the only one that's relatively easy to find. It's a McGredy rose, and he hybridized some of the best hand-painted roses. The one I like most is Stretch Johnson, sold by Palatine as Rock 'n' Roll most years.
Shrub Rose (Rosa 'Stretch Johnson')
Palatine also carries Regensberg, Little Artist, and Eyepaint
Rose (Rosa 'Regensberg')
Rose (Rosa 'Little Artist')
Rose (Rosa 'Eyepaint')
Other McGredy hand-painted roses that are more difficult to find, but are equally impressive, are:
Rose (Rosa 'Old Master')
Floribunda Rose (Rosa 'Picasso')
Rose (Rosa 'Matangi')