Well apparently mine is an H5 which seems to be advertised at 70 lumens so 700 may be overkill. 100 lumens is more than enough I think. There's a fair few non brand name ones on amazon, got to be worth a punt for 15 quid right.
It may depend on how technical the trail is & how tricky the nav. Worth a punt on a £15 er as it won't add lots if you find it's not enough, plus it'll no doubt have other uses - e.g. I wear cheapo headtorch when diy plumbing.
Erm, Petzl Nao ticks at least one of your boxes. Depends on your definition of not a lot of money (and how well you want to light things up).