Serengeti Accomodations

Sosay72,
Your post didn't mention where are you driving from, either from Arusha or Western Serengeti Corridor.
But, inshort, Accommodation inside the park you can't find any place match with your request of 15-30$, all the Hotels/ lodges ae charging more than 100-200$. So, may be if yoou have camping gear with you, you can use them, and also, this cost almost 30$ (camping fee at a public camping site)per person pernight, where you need to bring your own food and cooking equips.
Is possible to find local Guest house just out side of Ngorongoro Conservation Area, if your coming from Arusha,( I'm not sure if its self) and next day you can drive to Ngorongoro, but heading further to Serengeti there is no cheap accommodation in the Park, you have no option may be to cross out side on western area and overnight in the local hotel. (remmember that entry fees are paid once, -single entry)
So, try to think another option,

#1 is right - inside the park you have no choice but to stay in the lodges or camp. Even camping will cost more than $15 per person. For Ngorongoro, Karatu provides accomodation oitside the park. At Lake Manyara and Tanrangire you can also stay outside the park. Serengeti - no way, at least not coming from the Arusha side, as you will spend about 1/2 day just driving through the Ngorongoro conservation area and parts of the Serengeti before you even come to the Seronera area.

Outside the western corridor gate: Serengeti Stopover. Outside of crater but in NCA (I think): Kudu Camp. Both have websites and there must be plenty others - will find out more info next week when we start a safari following a similar route.

Thank you all for your input. We will be driving from Mwanza through Serengeti and eventually to Arusha. We hope to find something, possibly as suggested above, near Ngorongoro.
Again, thanks.