Hi all,
You can buy pretty much everything you want now in Kampala but quality may not be what you are used to, and the prices may be higher if they are imported products.
There is a big problem with 'fake' / replica products.
If you have a printer, for example, it is actually better to buy in Kampala because then you know you will find the cartridges et cetera you need.
As someone else suggests, bring medication if you have specific / uncommon needs. Health food supplements are quite difficult to come by.
These days it is easier to import things e.g. through international carriers, or visiting friends. I stopped using the post office about five years ago, but the service may have improved by now.
I've been living in Uganda as an expat seven years. You're very welcome to contact me via my blog