1950 Debutante Case back:BULOVA,L0 and serial# Inside case back:BULOVA,10K ROLLED GOLD PLATE BEZEL,STAINLESS BACK,NEW YORK 6BL 17 jewel movement is dated L0 Band seems to be original and is marked KREISLER .025 GOLD CONTENT U.S. PATENT. 2,064,760 BULOVA SIGNED CROWN
Looks like you even got the original bracelet. Cool. The ad above is 1948.
In the November 1954 monthly price list supplement, there's one Debutante w/ a new/updated price.
By the Spring 1955 price list quarterly, there's two entries for Debutante at a new/updated price. Note the Yellow Debutante "A" from Nov 1954 is 5787 and the Yellow Debutante "A" from Spring 1955 is 5136. This makes me thing there were two slightly different "A" variants out there at this time. Don't know how early this started.
1955 Spring new/updated price section.
Also in the Spring 1955 cumulative model section, there are several Debutante variants listed. The two 5787 "A"s have two different prices. 
