You cannot buy a visa on the border with Israel. About a year ago, representatives of Egyptian travel companies appeared on the border who sell stamps for 75-100 dollars each. Therefore, I recommend that you apply for an electronic visa at visa2egypt before traveling
+ 1 month to a valid visa that was received at the entrance - only a passport. If you request from 3 months to a year - 2 copies of your passport (person, visa), photo, fill out an application at the visa office.
At the visa office of Sharm el-Sheikh or El-Tour, or make a wound visa (in case of refusal to renew) through the visa office in Israel in Eilat.
A visa is issued for a month, after its expiration you have 2 weeks to extend or leave the country.