Buying a plot to speculate in Kampala will not pay you because you will not see buyers. People in Kampala are not as liquid as in Nairobi.
What will pay you is to develop your plot and sale, this will attract foreigners and a few buoyant Ugandans (at home or diaspora). Be aware that it is far cheaper to build in Kampala than Nairobi, they have a better soil, you can opt to build a brick house rather than cement house. Bricks are abundant and cheap especially if you are erecting a bungalow.
When buying land, be careful to avoid being conned, as a rule buy from reputable real estate firms so that you have rest of mind. It might be more expensive but is secure. It also affords you instalmental payment plan so you can spread payment ranging from 6 to 24 months.
Your best bet on upcoming area is Entebbe road suburbs, or Jinja road (Mukono etc). I strongly suggest Entebbe road environs.
Two top real estate firms in Uganda tested and proven are
(i) Akright Projects
www.akright.biz(ii) Jomayi Estates Ltd
www.jomayi.co.ug Your 500K KSH is a lot of money in Uganda terms
You are referring to 500,000 X 28 = 14 Million Ugandan shillings !!!
That can fetch you one or two good plots in an upcoming neighbourhood.
I bought a plot with Akright project a little over a year ago at 12 Million UGX, the payment plan then was 30% down payment balance spread over 12 months.
Confirm from your agent the land tenure system as applicable to the land on offer as not all lands are available for foreigners (confirm whether the land is freehold or mailo). In addition be familiar with the dimension.
If I may recall a plot of 50 X 100 feet is 12.5 Decimals and so on.
As a Kenyan in Kampala, I am not sure whether you are categorized as a foreigner (as per East African Federation
In essence do your due diligence.
Uganda has a bright future if you are looking beyond the current dictatorship. It is a question of time. If it happened in Egypt and Cot'Ivoire, there is hope for Uganda.
The wazua spirit as members is to educate and inform and learn from others within the limit of what we know in any chosen area irrespective of our differences in tribes, nationalities, etc. .