A LONE4 bought in Egypt is around $575 less than the same ticket bought in the UK, for example. If you can buy a round trip ticket from your home to Egypt for less than $575 more than a ticket to the UK, then you can save money by physically flying to Egypt, collect your ticket, and start your RTW there, knowing that you have to return to Egypt (or actually any city within the Middle East) within a year to end the trip, then use (if it's still good) the return portion of your original round trip ticket to get back to wherever you started the Egyptian odyssey.

Unfortunately, most RTWs are long enough (in time terms) that really cheap return tickets to/from the start point - Cairo, Istanbul, wherever - from places like the UK or the US aren't valid, because they aren't good for more then 3 or 6 months, past which the price goes way up. It's okay if your start point is served by low cost airlines that offer cheap one-way fares (Poland was good in that regard, for instance) but not so hot if your start city isn't well served, or if it's served seasonally (most always the wrong season in our experience.)

Use the sticky to see where some candidate cheap origin points might be - maybe places you wanted to see anyway, like Croatia - then you begin the challenge of finding someone in the origin country/city to issue the ticket. Cairo is popular because one or two travel agents there are real xONEx pros; our experience in IST with BA's local office was also very positive. But to be fair to your budget, you need to factor in the cost of getting to the takeoff point in the first place, as well as the cost of the actual RTW tickets once you get there.