Cheapest form of powered aviation is foot launch Paramotors....or powered paraglider. I fly a Scout and Ozone wing.
No license required under FAR Part 103 which is a whopping 2 pages that govern us vs the Bible that is Part 91 (from which 103 is exempt except as noted in 103). Once you own the gear they burn a whopping gallon an hour, no hanger fees, Mx is virtually zero cost, and you can slap them on the back of any vehicle for transport with a hitch tray or bike carrier.
Once you buy the gear, your operating costs are negligible (except for all the trips you will then be taking and PPG fly ins you will be gong to!).
$2,000-$3,000 for training
$5,000-$9,000 for motor
$2,500-$4,000 for wing
Less if you can find used but you do not want old gear. The equipment has rapidly evolved over the past few years.
Now the down side is that they are VERY dependent on good weather and in most parts of the country can only be flown a few hours after sunrise and few hours before sunset which limits flying window. Mid day thermals can be bumpy if not unsafe to fly in.
I have had a LOT of different toys over the years and It is by far one of the cheapest forums of any motorized sports let alone aviation. I fly my 182 for transportation, I fly my paramotor for fun. They are like a jet ski in the air...you can just cruse and enjoy or rip around with insane acro once you build skills. PPG is legal in both G and E airspace.
Here is quick edit from a Mt Shasta trip we did a while back with 9 pilots.
Random pic for reference: