To Trek in Bale National Park a guide is technically required, though I met a couple of Alaskans who managed without one. Once you get away from the guides at the entrance no one is likely to care. I attempted to take the requisite guide intending to trek as I had in the Simiens carrying my own gear, but none of the guides would go unless I also took horses, as I was on my own this started to jack up the price quite a bit, past the threshold of what I was willing to pay per day. I instead opted to take the day hike solution. It is not required to take a guide when hiking "around" the park headquarters (around the park headquarters is subject to interpretation and I probably stretched its meaning considering it anywhere I could hike to in a day but really no one cared).
I stayed in the dorm room at the National Park lodge, there was no one else there so essentially I got a room to myself for a fraction of the cost of the double room. Your better off hiking into town for food at one of the reseraunts but the caretaker will likely offer to bring you a simple breakfast for an inflated price for the convinence. There are also some simple guesthouses in Dinsho but its nice to be able to see wildlife right outside your room even if it is less convient for eating though you could also cook your own meals.
Do It Yourself Information
A couple day hike objectives from could be the Finch Abera Waterfall and the upper Web River valley. The best place to see wildlife actually is the area right next to the park headquarters and the lodge. The farther you hike from here actually the less you are likely to see. Another good area is the valley along the road east of Dinsho.
For Finch Abera Waterfall take the path northeast out of the eastern end of Dinsho, basically anywhere after you cross the bridge on the main road should eventually get you in the right direction. Continue to veer towards the northeast and eventually you'll hit the river. There will be a well worn trail that heads down to the river where there is a bridge to cross the river upstream from the falls. For the best view of the falls follow the path south on the east side of the river until you get a view of the falls. You can backtrack to the bridge and then hike the trails that head up to into the hills to the northeast for some nice views out over the the valley. This is also an area where there are suppose to be Ethiopian wolves but you will need to camp to have a good shot at seeing them since the chance for sightings are highest early in the morning.
For the Sanetti Plateau which is the area where you have the best chance of seeing Ethiopian wolves you can take the first early morning bus from Goba towards Dola-Mena and hop off on the plateau. I was prepared to camp a night on the plateau but I was mainly interested in seeing the Ethiopian wolves and after I saw one and hiked around for a couple hours, I decided to hop on another bus heading back down to Goba, rather than spending a cold night on the plateau. Your best chance of seeing wolves is early in the morning to about an hour or two after sunrise, the bus will likely get you up to the plateau at the end of this window so for the best chance to see wolves you may have to camp overnight, or hire a vehicle to get you there earlier.