Asklemmy

Rc cars. I got a crappy 1/6 scale truck (newbright) for shits and giggles to see what it could all do before I fried and broke it. Ended up slowly dumping a bunch of crap into it (Batteries, lights, new controller, esc, new brushless motor etc)

Wouldn't have been quite so bad if it was a "normal" scale rc, but parts for something 1/6 scale is pretty pricey. I could have just bought a better machine, but it was still fun and I learned a bit about rc stuff. This is the frankenRC https://i.imgur.com/ey1jJYX.jpg

Disc golf.

Discs cost only $15-20 new, used ones can be only a few bucks, you only need one or a few to play, and most courses are free.

In reality, you keep buying new discs. And a bag to carry them. And more discs. And a bigger bag. Then a home basket. And a net to practice in. And more discs. Then a rack to hold the extra discs you can’t bag…. It adds up!

Camping and camping gear. It can be so cheap and easy, but when you start buying high end gear it adds up quick.

Not to mention the different types of camping, backpacking, car camping, glamping, etc. Car camping “overlanding” gear is awesome, but so expensive.

Thinkpads.

Hobby electronics started cheep, with a crappy soldering iron (a good precision one was the best purchase ever) and some cheep parts, ended up with a room stuffed with a thousand dollars worth or parts and a few thousand more in test equipment.

ITT: Everybody's current/longest hobby.

Mine is boardgames. You start free by playing somebody else's collection, then you get the urge to start your own...

Film photography. Holy shit did that add up.

Electronics repair and projects

Coffee for sure, never saw myself owning a $300 coffee grinder a few years ago....

Smart phones and headphones aren't exactly cheap but, I have built a bit of an expensive hobby around collecting them lol

When I first got into my hobby (DJ) I thought I only needed to pay into the set up cost of buying equipment (turntables, mixer, sound), but I eventually learned that I had to keep buying records because I couldn't just mix the same two recorded forever, and that got expensive.

Beekeeping. It gets expensive very fast and doesn't seem to ease year on year

For me it was Badminton. You can start off with cheap $15 rackets and plastic shuttlecocks. Now my racket is $260 and I play with feather shuttlecocks which are about $2 a piece and only last a few rallies.

Knitting/crocheting and cannabis. Not (always) together. Yarn art to pass the time while sitting with my mom - I start a lot of things and always need new yarn, but I never finish anything. Cannabis because I started making candies for a sick friend and it's pretty easy to get caught up in different strains and what's on sale this week.

Fountainpens. Started with some cheap Chinese pens. Now I have multiple vintage pens and a Montblanc that I love writing with.

Collecting vinyl records. I started 10 years ago when you could get lots of records for 3-5$ per record. Now everyone is crazy about collecting and they can cost 40-50$. Was a great investment if I sell them. But I enjoyed collecting them regardless of value.

Bonsai

Playstation 4. Huge money went into buying discs and digital games.

Believe it or not, self-hosting! I went from renting a VPS for $40 a month, to purchasing an entire $150 machine at home, plus $50 or so in additional storage, plus a $20 a month VPS solely to bypass NAT restrictions... plus a few hundred dollars more when I first started, because I cheaped out on components and managed to brick not one, but two Intel BIOSes trying to update them.