It is not that difficult to do it yourself! Which bits do you want someone else to install? The aerial does not need to be the backstay (which would require insulators and thus probably need riggers - but this is expensive and unnecessary). It could just as effectively be a stand alone aerial. This is cheaper and arguably more efficient. Similarly you may think you need an earth PLATE, but again depending on your hull material you may find concertinaed copper strip in the bilge just as effective. I have searched S Portugal for that without success! Readily available from UK HF suppliers.
A search of this site should provide info which I (and others) have previously given or will try again if you need it.
I am sure in Lagos you will find those able to do it for you.
