I have tried those websites you have mentioned. I was just seeing if anyone has real world experience of living in any of the surrounding areas and what to look out for.
If you want to be practically on top of Camden, Kentish Town is great, and you could probably find something within your budget, though not sure that the cost of parking would be covered in that budget. Having a car in London is expensive as all get-out.
If you don't mind a 20-minute commute, look along the Overground from Camden Road station -- Kilburn to the west would be in-budget, and Stoke Newington to the east as well. I live in Kilburn, and I adore it, although I realise it could be an acquired taste. My best mate lives in Stokey and really likes the neighbourhood feel, though he mostly takes advantage of the pubs and not the green spaces.