No such thing as a "cheap hobby" unless it's watching the neighbor's grass grow. If it's YOUR grass, you have to water it, that costs $$, or mow it, you have to buy a mower.
Just about everything we touch costs $$. You like to hike? You have to get to a starting point one way or another.
Build model airplanes? $$! Start flying them? More $$!!
Build guns? $. Shoot guns $$!
Whatever you like doing, do it because you like it. You can't take it ($$) with you unless you can change it into Travelers Checks. And you're only going around one time (unless you're Shirley Mac Lane) so enjoy the hell out of it!!
Photography. That gets expensive REAL FAST but very fun.
Building street rods? EXPENSIVE!!
Growing Bearded Iris? Try 2500 plants. New catalog? More $$$.
Making quilts? Took the wife to a Quilt show, figured I could make those. Cost me a couple $100 for fabric before I got home.
Try Stamp collecting. One cheap (Mint) stamp cost $450.00 +. It goes on from there.