I'm always on the lookout for a decent nato supplier and discovered these guys a couple of weeks ago. I usually favour Eddie's but as it can take up to four weeks from the point of wanting one to delivery from Timefactors I'd rather go elsewhere. I've now bought three of the seat belt variant and they're really very good! Delivery is quick too, always been here the second day after ordering.
No affiliation whatsoever, just good quality straps and decent choice of colours.
http://www.ebaystores.co.uk/Power-Save
I'd second that. I've got a couple of their seatbelt Natos and they're pretty decent and very good value at the price point.