As
@An Ankoù said, 5Kgs of any pale malt will do the job, then…
Bitter
A pack of cheap yeast like SO4 and a pack of cheap flavoursome hops like Fuggles
Pale Ale
A pack of cheap yeast like SO4 and a pack of cheap flavoursome hops like East Kent Goldings
Saison
You already have the yeast so just need a pack of cheap flavoursome hops like Styrian Goldings
Pilsner
For this one you want 5Kgs of cheap lager malt, a couple of packs of lager yeast (use Mangrove Jacks M54 if you don’t have good temperature control) and a pack of cheap flavoursome hops like Saaz.
There’s loads you can do with very little but that will probably suffice as examples.
Also remember if you want a bit more strength you can add a little sugar. 500g of table sugar will add around 1.5%.