i did it in 1998. i think our 3 days cost something like 200 quid. we stayed in canvas tents outside the masai mara and then got taken in on a mini bus every monring and evening. very basic accommodation as it was just a camp bed under a tent and there was no hot water showers. food was filling but not amazing. needless to say it was fab sat around the table in the evening with all the sounds around but it was also a bit scary knowing that there was no big fences to protect you, only a night watchman.
edited to add, we were a with a company and we had guides/drivers take us around and who also did the cooking. cheap and probably as independant as you're going to get.