I think the main problem they've had with getting some memorable housemates is that they simply don't want to do it anymore. Both Kate and Aisleyne have said they had "moved on" from that time of their life.
There have been conflicting reports on payment. There were rumours that the All-Stars would be paid £30 per day, which Nikki denied on BBLB. Billi Bhatti claimed that Sharon Powers, the executive producer, told him that no-one was getting paid, and claimed he found out that a few would be paid a large amount of money - he claimed that Brian Belo would be paid £10,000. But not a lot is known about who is being paid what, if anyone is getting paid. It'll all probably be kept hush-hush.