I hope The Most Beautiful Girl in the World is going to be available on Apple Music here in the U.K.
TMBGITA was an independent release, so not part of his Warner Bros catalogue. That explains why it's fallen to the wayside. I've always considered the effort and promotion of that song to be an FU to WB from Prince.
Have you looked at buying the single and related releases such as The Beautiful Experience second hand?
I understand that some artists are big about promoting lossy music, but for older artists it seems a bit odd. After all, most of their sales were on vinyl or tapes, which wouldn't have anywhere near the quality or lack of deterioration that you'd get from 256 AAC.
The sound quality of Prince's music in particular has been pretty lacklustre. I assume due to poor mixing, and not related to the final medium. It can only improve with remastering.