That seems low as a starting price for a 313 roadster with only 10k miles, looking on autotrader similar specs are asking just under £15K. Hard to say though without full info and pics, we don't even know if it's a UK car.
I think your both way too high!
Jamie Moy has had his car up for sale for months and his is newer with less mileage. Think it is currently for sale at £12,995................
I was being generous and considering the fact its mint with 4 new tyres. 13k seems a bargain to me, shame i'm not looking for a 313 roadster now. Prices still seem to be all over the place when it comes to 350Z's.