The issue is that those children who would most benefit from sensory products all have different needs!
This is an area that if money is going to be spent, then you really need a sensory trained OT to come in and advise the nursery.
It's really important that nursery staff understand that the term SN isn't code for "low expectations", as one size doesn't fit all by a long shot.
It might of more use to have a quite space for those children that get upset (a comfy soft cushion in the book corner?) & some caring cutlery for those who find difficulty eating, a joystick as well as a standard mouse at the PC, a movement cushion for use at the art table, large print books etc, etc. An OT would advise.
I'd suggest instead small range of specialist equipment that will facilitate the INCLUSION of various SN's within the main nursery peer group & reject the sensory room suggestion outright.
I worry that some SN kids will wind up spending all day, every day alone in the sensory room instead of LEARNING and engaging with their peers. The staff will then pat themselves on the back and tell themselves that they are doing a great job, having barely said 2 words to the poor kid concerned all day. This is a real risk 
(btw- My own child benefits hugely from a personalised sensory diet at school, that many other children would find torturous.)