You're seeing some lovely watches here that are manual wind, meaning that they will need to be wound every day. If it says "automatic" on the dial, then it will charge itself while being worn and won't need the daily winding.
If you think your husband would be happy to wind it every day, then a manual wind is normally cheaper and is definitely cheaper to service. Most of us don't mind this but it depends on the person.
With manual wind and your budget plus wanting it on a NATO strap, you have a large selection. Something a bit different that I have is this Chronostop (145.007) which I just put on as I've finished work for the day. It's somewhat larger than the others but is a sixties watch.
The choice of sixties Omegas is huge and definitely something for everyone.
By the way, if your husband was in the forces, you can often find a NATO that suits his unit (colours and so on).
Good luck, Chris