I guess if all you want is geocoding, you could exclude a lot of data before importing it. Eg landuses without names, lots of single nodes that have nothing to do with addresses, etc.
Have you set it up? I have...and I am giving you the amount of time it took to do a world import on data from January. This was on a quad core xeon 5345 with 32gb of ram and a dedicated SSD for swap, with database living on a RAID10 of 8 7200 rpm drives. In other words, the box is decent.
I am not trying to fear monger, I am just trying to say "hey, BTW unless you have a big hardware budget, you might want to just pay a third party".
There are some numbers available at http://wiki.openstreetmap.org/wiki/Osm2pgsql/benchmarks (eg getting it into EC2 in a day for ~30USD). Even just a week would be a pessimistic estimate.
I guess if all you want is geocoding, you could exclude a lot of data before importing it. Eg landuses without names, lots of single nodes that have nothing to do with addresses, etc.