Here is the most accurate info to date and hope this proves useful...
The bus service with MAZADA TOURS runs twice weekly as follows:
Every Sunday and Thursday,
leaves Jerusalem office at 15 Jaffa St.at approx. 08:30
leaves Tel Aviv office at 141 Ibn Gvirol St. at approx. 10:00
Currently, the R/T bus ticket leaving either Jerusalem or Tel Aviv
for Cairo is priced at US$165.-(includes exit/entry fees but excludes US$15.-visa)
Holders of most foreign passports that travel on the bus are guaranteed a stamped visa
at the Taba border.
R/T airfare with Air Sinai Tel Aviv/Cairo leaving 4 times/weekly, is priced at US$395.-