It is a south African made MkII distinguished by how round it is and the three holes in the rear of the rim, I cant comment about price though but an un-messed with one went for around £150.
South African helmet, I think the chin strap my be an Israeli replacement. looks good and used though, price doesn't seen too bad if it is what you are looking for.
Nice helmet although the chinstrap is not SA wartime.
Thanks everyone for the info! How easy/hard to get an original chin-strap for this?
SA helmets were widely used by Commonwealth troops in North Africa, not only by South Africans. Indian troop contingents often had them, even English sometimes got them. In general 8th Army was a large mix of equipment and nationalities.
A British mk2 or mk3 chinstrap will be correct for this helmet, should be easy to find. Price is ok, but could be cheaper because of the chinstrap.