With 9 days in Uganda if you get your skates on and are well organised you really could do quite a lot. Your itinerary would be dictated by the date of gorilla tracking activity. If you travelling between Feb and April you will have a good opportunity to secure a permit for your preferred date of tracking. Anyhow to give you an idea of what could be achieved from my own experience would be.
Day 1. Arrive Ebb and transfer to Red Chilli Hideaway and stay in their one of their self-contained cottages. Airport transfer Ushs80,000- and accommodation for Ushs100,000-. This meets you budget of USD100-.
Day 2. Participate in one of Red Chilli's 3 day 2 night Murchison Falls Safaris that includes accommodation, transport, park fees and activities all for USD180- per person.
Day 3. Murchison Falls National Park
Day 4. Return from Murchison Falls to Kampala. Take private hire into the city to stay at City Centre Annex Hotel close to the National Theatre. A great double room here costs Ushs50,000- with some good restaurants close by.
Day 5. Take private hire vehicle to bus park and take bus to Buhoma in The Bwindi Impenetrable Forest (Ushs25,000). Budget accommodation double at Bwindi View Banda's or Buhoma Community Restcamp for about Ushs80,000-.
Day 6. Trek Mountain Gorillas. Overnight in either of above.
Day 7. Walk through the Bwindi Impenetrable Forest (6 hours) to Nkuringo and overnight at Nkuringo Gorilla Campsite. Twin room Ushs35,000-. You need to pay park entrance and escort fee plus Nkuringo Walking Safaris www.nkuringowalkingsafaris.com</a> guide fee of USD50- total per person.
Day 8. Walk 9km to Rubugiri and take private hire vehicle to Kabale (Ushs150,000-). Accommodation at Edirisa or Queens Guesthouse. Double Ushs20,000- to Ushs30,000-.
Day 9. Board 03.00am Kalita bus directly to Fort Portal from Kabale (Ushs20,000)-. Arrive Fort Portal and proceed to Chimpanzee Forest Guesthouse double room Ushs120,000-. Private hire arrangement (Ushs30,000-).
Day 10. Track Chimpanzees in Kibale Forest National Park. USD70- for tracking permit. Transfer from the guesthouse to the forest and back to Fort Portal Ushs50,000-. Take Kalita bus which departs every hour to Kampala for Ushs11,000-. Arrange private hire transfer to airport or Entebbe accommodation. Highly recommended would be Entebbe Airport Guesthouse where a twin room is USD50-.
I am sure this programme comes in on your anticipated budget and of course relies on your resourcefulness to essentially 'do it yourself'.
Having someone on the ground in Kampala to set up the venues and contacts would be in your interest. If you need further knowledge PM me.