Cost for TR Classic, I have seen around £11.500 + Base check £6000 + VAT.
And to do get NG from Classic you do a differences course, approx. 8 hours in sim and ground-school, seen it quoted for around £1600.
These are prices I have seen if you just search around, pretty much average European prices.
Several companies in Europe also fly the classic, Astraeus, Norwegian, to mention a few.
Who said you could not do a differences course, to get the NG?
As a little extra note, maybe a job in Africa if you have a rating, unless you know this company very well, take this with a pinch of salt, there are loads of scammers out there promising a lot, when you get the 737 rating they might say if you only had an Airbus rating too! If you get my drift, be careful, there are loads who give empty promises, some written might not even be worth the paper they are written on.
So make sure you do your research properly first, I have heard few horror stories of African dreams gone pretty sour for various reasons!
A promise does not mean to much, maybe you get a TR, but without hours it is not worth to much, maybe you get a job, but discover major maintaines issues, airworthiness issues etc., I have met many people in business life who have promised me the sky, the moon and whatever else, just make sure your contact is not a bull****ter!