What a bizarre thread this is. No offense, but to begin with it's pretty difficult to make sense of exactly what you want and intend to do with the gear. First it's vintage, then it's 50 Cent, first you ask for high end, then you reply you can't afford it (Sony C800G).
The first question you should ask yourself imho is whether you really need this high-end equipment. It seems that you have a small homestudio and want to record your own rap / R&B music, correct? In that case, do you really need the equipment of the likes of Dr Dre and 50 Cent? Besides there will be many more factors that come into the equation than just the mic and pre, for example converters, comps, room treatment, etc. This can quickly add up to a chain costing $30,000+. Why not prepare the music with your current equipment at home and then record vocals at a professional studio boasting all this high-end equipment and save a lot of money that way?
But if you really want to take the plunge - how much can you spend? And what would you want to spend it on? Why focus on the pre if this will arguably have the smallest impact on your sound? If you really feel you have to spend your earnings then invest in a great mic and a great comp, these will help you achieve the "in your face" sound much better. If, however, you think this advice is utter shite then let me close by saying (like other posters) that you can't really go wrong with any of the listed pres. Depends on your budget and your preferences. I've used the BAE 1073 and the Aurora GTQ2, and they're both great.