The Mara is really three places to sleep — the national reserve, the Mara Triangle over the river, and the conservancies to the north — and they differ in rules, not just in price.
Inside the national reserve
Camps within the reserve boundary sit closest to the Mara and Talek river crossings and let you start driving at first light without a gate run. In return you share every sighting with whoever else finds it, and you pay reserve entry for each 24 hours you are there.
The Mara Triangle, west of the river
The reserve's western third, across the Mara River and backed by the Oloololo escarpment. Separately managed, markedly fewer vehicles, and only one lodge actually inside it — the trade-off is that you are a long way from the busier Talek side.
The northern conservancies
Naboisho, Olare Motorogi, Ol Kinyei and their neighbours, on Maasai land outside the reserve. Vehicle numbers are capped at sightings and night drives and walking are permitted, but bed-night levies make them the most expensive beds in the ecosystem and the river crossings are a drive away.
Talek, Sekenani and the gate villages
Practical tip: the trading centres at the reserve gates hold the cheapest beds, along with dukas, fuel and mobile money, and are where drivers and guides stay. They are dusty roadside settlements rather than a base with a view, but they cut costs sharply.