So, say your beloved 18-55mm lens that had served you so well suddenly broke, with the cost a repairing being near as much as a new one would you repair or get a new one?  In the case of a new lens, which lens would you get if it were to go on a Nikon D90?  I am tempted by the 18-250mm lenses and am saving hard for something near the $1000 mark (it's hard going with all my medical bills) but I want something with a low f stop.  Can anyone recommend anything for me?  I borrowed a friends 18-250mm Tamron lens earlier in the year and have an 18-70mm Nikon Lens on "permanent" loan but I really need something of my own.
Please, when commenting, take into account the vast range of photography I am doing!

Many thanks,
Amy