8 year old boy party that's not price per head

[Illbewithyouinaminute]

I'm trying to think of party ideas for my ds.

There are people he wants to invite, and then there are people that we/he is obligated to invite. So looking at between 20-30 guests.

Trying to think of party idea that is about £200-£250 in total, so looking at hall type party rather than per head party.

He likes disco, but don't think (and could be wrong here) most 8-10 year old boys like disco parties.
He doesn't like magicians, science acts, type entertainment i.e. the ones where it is a show and the majority of audience rather than chosen few sit and watch.
Thinking of maybe pool party, but could become unstuck with the 7 year olds and getting into adult ratios.

Has anyone got any other ideas? I'm in the South, but suggest all ideas regardless of location incase I can find something similar locally.

Pool? Sports?

Fancy obstacle course type bouncy castle, or the wrestling type bouncy things?

football centres often do parties?

Had thought football which he loves, but a number of his friends don't enjoy it.
Inflatable good idea can you have obstacle course ones indoors does any one know? (Of course subject to the room being big enough) or do they require ground to tie into?
Winter party, so outdoors not an option.
Thanks for suggestions.

We did a swimming party for DD - up to 25 guests cost £85. Just had to provide some grub for them afterwards which we did ourselves as well. With Party bags we spent total of £130.