Are there any such fonts out there?
The long s 'ſ' can be found in many blackletter fonts, but the r rotunda 'ꝛ' seems to be very rare. There are several blackletter fonts by Peter Wiegel (Cat Fonts) that contain both glyphs and are for free:
Of these, Rotunda Pommerania comes closest to the blackletter type used in that incunable in Wikipedia. It's called rotunda (German: Rundgotisch – 'round Gothic'). However, Pommerania doesn't seem to have a standard 's'. You should also refer to the ReadMe files for infos on input (e.g. type '&' for the 'ꝛ'), since the fonts are not in OTF.
Download page: http://www.fontspace.com/peter-wiegel
Both characters are also in:
(They are also featured by Google Webfonts.) Download page: http://unifraktur.sourceforge.net
More blackletter fonts featuring the r rotunda are downloadable via Peter Wiegel's own website: http://www.peter-wiegel.de/fonts2.html