Reading some commercial tour reports when planning our trip, it did look as though Dolomite is a reliable spot for Hartlaub's. It looks a really nice camp, but was beyond our budget.
Another really good budget option at Erongo is Camp Mara, which has cheap camping and is adjacent to Erongo Wilderness Lodge. The owner feeds birds on a pretty industrial scale, with literally hundreds of Rosy-faced Lovebirds coming in to feed a few metres from the breakfast table.
We were told that several European airlines have recently commenced direct flights to Windhoek from Holland and, especially, Germany, and that this has greatly increased the number of tourists. Even though Namibia is huge, all those tourists are going to the same relatively few places, and I guess it's inevitable that increased demand without increased supply is going to push prices up.
The good news is that there are (mostly) very good camp sites at or close to pretty much all the major birding sites. Apart from Etosha, these are typically about £10 or less pppn.
It's also much cheaper to hire a car in South Africa and drive into Namibia, if you have the time and inclination. We did a loop from Joburg down to southern Namibia via Kimberley (Marrick Game Farm), up to Kunene, across the Caprivi to Kasane and back to Joburg through Botswana, via the Boulder Chats near Francistown. It's a lot of driving, but you might as well be sat in an air conditioned car putting the miles in during the heat of the day!