Haven't heard it for yonks, but I have in the past mangled the (Pete Seeger?) 'A Dollar Aint A Dollar Anymore' for this sort of intent.

The snippets I can recall:

I was feeling rather hungry so I thought I'd buy some bread. I went down to the corner grocery store, I took out the usual money but the grocer shook his head, Cos a dollar aint a dollar anymore

Chorus

No, a dollar bill won't. Buy what it used to X3 A dollar bill won't buy what it used to, Cos a dollar aint a dollar anymore.

From the knockshops in St Kilda to a frosty Fosters can, You find now that you get less for dough, Let's Canberra by the collar, 'Pull those prices back' we'll holler. Cos a dollar aint a dollar anymore.

And just composed on the spot:

Now we’re used to paying taxes, levies, rates and subsidies, P.A.Y.E., I just uphold the law, Yes we’re vengeful, mean and spiteful, This country’s had a shiteful, Cos a dollar aint a dollar anymore.

Cheers John

PS The tune in the chorus is vaguely similar to The Old Grey Mare.