My thoughts
Hi there, cheapest way into the bush, I think: 130 - 150 hrs in gliders (do that in the UK, start now, include 30 hrs in TMG - you can still count these later for the CPL/ ATPL, and try to make as many of these as possible as cross country flights of more than 50 nm straight line distance), study everything you need ahead for the FAA written exams (Private, IR, ME and CPL), and then go to the States with a small mom & pop flight school under Part 61.
150 hrs in gliders can be validated for the 250 you need for CPL ME/ IR, but in all honesty for the PPL/ cross country building etc. you will probably need 120 hrs anyway. Include 30 - 50 hrs in the FNPT for the instrument training - and THEN with all the money you have saved you can be happily pursuing either jobs in Africa or build your experience by towing gliders, dropping paras etc. If you don't make 130/ 150 hrs in gliders until next year, get a taildragger rating and some aerobatic lessons stateside, it's gonna make you a better pilot and more likely to allow for more hourbuilding (glider towing to my experience is often enough done in taildraggers, just to mention it). Everything else afterwards is covered in other forums (P2F, SSTR, self-sponsored line training etc.).
However, if you have the funds of say 60 k $, go to Aviator.edu and instruct with them after your CPL ME/IR. Not sure how short they will be of instructors in late 2013/ early 2014, but if you go on an F1 visa, teach for about 12 months OPT I am sure it will greatly enhance your employability in Africa as opposed to wannabes like me with 300 hrs.
Oh, chief pilot at Aviator is a former glider pilot and (French) naval aviator, since they combine 141 and 61 in their syllabus there might be some hours you won't need in a 120 $ per hour aircraft if your logbook is full of UK glider time. Just a thought...
Just my 2 cents, and good luck!