I am traveling to Uganda for a gorilla trekking.I have booked the trip but would like to short trip around kampal.Any ideas.
Also accomodation in Kampala for about 25-30 dollars for a double.
Kindly advice.

Around Kampala -
Mpanga forest
Ngamba Island Chimp reseerve
Entebbe
Munyonyo - Speke resort is nice - by the lake etc.
Bahai temple
Wamale Tomb
Alternatively, you could have a wander around Buganda culture, visiting the Kasubi tombs, Bulange building (parliament), Twekobe (Mengo) palace and Amin's torture chambers...
Manhattan Guest House has reasonable rates and has a decent location on the West side of the city near Namirembe.

If you have a day, I'd go rafting at Jinja. It's just 2 hrs away on a good road.
You can visit the Kasubi tombs but there was a fire and they're (still) rebuilding the place. You're not going to see much. Quite underwhelming really in its current condition.

You can add Mabamba swamp looking for shoebill among papyrus and liliflowers...
a nice trip on local canoe.
The mosque is interesting, offering a 360° view on Kampala from the minaret.
If in Kampala on Wednesday, Friday or Sunday, don't miss Ndere performance.
I know a good reliable guide/driver if you need one.
If you need more info or contacts, here is my private mail (removed)
Uganda is so wonderful...enjoy, you are lucky to travel there.