Alternatives to expensive air fresheners?

Yes, not having pets

My parents use one of those air fresheners that pumps out a different fragrance every 10 mins. I can't stand the thing.

I only have an expensive one for you but I think that one the whole it's probably more cost effective, smells nicer and lasts longer, etc ... those reeds that are then placed in a bottle of plum/jasmine etc perfume. Every time the fragrance starts fading you turn the reeds around. I have had mine since Christmas and they are still going strong but they do cost around £40.

Have you tried bring home some wild flowers cut from the hedges. Costs nothing and it a lot more attractive than a plasic air freshener.

Throw open the windows every morning for half an hour!! That is true air 'freshening', everything else is pong masking, unless it is a genuine neutraliser!
Instead of shake and vac type things, use bicarbonate of soda, which is nature's own odour eater.
A few drops of essential oil somewhere where it gets warmed - in a sunny window, on a radiator - Lemon is invigorating, Lavender great in a bedroom as it is very soothing, Rose improves mood, Jasmine is sensual (!)

Happywriter, I think you get into trouble these days for picking wild hedge flowers because all the birds and bees need them!

In that case, you could just live in a hedge instead?

I expect it's pretty carbon neutral too.