That sounds quite a lot to me, but as others have said, everyone has a different budget and I can see how you could easily spend it if you had it.
We probably spend about £50-80 on gifts unless they need something like a musical instrument or bike. DS is turning 10 next week and is getting a football shirt £35, plus some slippers, a puzzle, 6 books, some bouncy handballs and a carnivorous plant.
Party is for 4 friends plus my 4 kids, going to a trampolining centre which is £6 per kid. Will buy takeaway pizza and drinks and I'll make a cake, so I guess £70 for the party.
For those wanting cheap party ideas, we've gone on a 'stick hunt' in local park then walked home, built a 'campfire' and toasted marshmallows and sausages, had a "mystery dinner party" (menu written in code), a cake decorating party, treasure hunt or photo scavenger hunt in local park and streets, craft themed parties...all cheap but all rely on a space at home and/or good weather (we aren't in the uk).