It feels like this question wants to be saying "what price did you buy bitcoin"? :-)

Buying a 1 year commitment to my gym; I went from a bad cholesterol of 421 to 189. Amazing drop, 3 months in and I've lost 30 pounds and significantly reduced my A1C and other factors. On target to lose 100 pounds.

This might not be the answer that you are looking for, but a good set of peripherals for my PC.

A good mechanical keyboard, 3 decent screens, a stand to mount them up high and make room on my desk, and a few other smaller things.

Those parts have done more for my career and sanity than anything else I could have spent my money on at the time.

I spend 40+ hours a week at or around this desk, I want it to be comfortable and work well for me. Not to mention that even if something makes me 1% more productive, it's worth it to spend $1000 a year on it and still "break even" in terms of cost (in theory)

I bought a business/website while in school for about $400. This year I anticipate earning about 7-10k from that site.

It was a great investment for the financial return alone, but I also learned a lot about business, marketing, and the technical skills needed to run the website.

The AWS bill for my first personal website. Being able to say "I built a website on AWS" in 2009 was probably the reason I got my first job making >100k.

technically, it wasn't my investment, but my Father bought me a PC when i turned 13, and that cost about 800EUR at the time (close enough to $1000)... i got hooked on computers, and have been working in the field for the last 13 years full time.

Buying 4.16 bitcoins in 2015 for $240 a piece.

Joining a dating site. Met my wife a week later!

Prepaid a 1 year gym membership. Returns will be non-monetary.

1,000 BTC at 0.70 in 2011...

I bought $1000 worth of Ford stock at its all time low after the market crashed. Incidentally, I also bought $1000 of TSLA when it was in the double digits per share. Too bad I sold it for like a $100 gain (edit: total $100 gain, not per share - I figured 10% was a nice gain and to not get greedy).

I've made enough bad stock calls that I don't regret putting only $1000 in those, though. Those just happen to be my winners. We might need an Ask HN on our worst $1000 developments :)

When I was younger, I was frugal about everything. I scrutinized every purchase with "do I REALLY need it?" Sometime later I figured out that if the thing is going to help me get closer to my goals (books, productivity enhancers, computers...etc) and was affordable, then just buy it. Or if it will save me time such that I can work on something else (i.e. Pay someone to mow the lawn), also worth it. This thinking has substantially changed my life for the better.

Probably my iPhone SE. Bitcoin made me richer, but I didn't get on early enough for it to have made any real difference, where as the smartphone changed my life.

That or my cat.

Under 1000$ I did a life design workshop in Montreal for 40$. In just 3 hours I figured out what I really wanted in my life. Thanks to the workshop I now make 300$ more a month on a side project, moved to a house with a jacuzzi where I can rent the basement out (about 400$ a month and communal life which I love), and negotiated a 5 hours a week reduction in work.

The reduction of hours might cost more than 1000$ though... but it is well worth it!

I bought a round-trip plane ticket to Shanghai China for $900 to attend the Ethereum developers conference when I was completely broke. The conference inspired me to get involved with Ethereum development. Even though it was a lot of money for me to spend at the time, it ended up as one of the most rewarding decisions of my life.

AAPL at ~$12/share in 2000 (price not adjusted for splits).

I bought a 1992 Subaru Legacy for $700 cash. I put some parts in it and drove it for 4 years. Survived a couple fender benders during that time too. I gave it to a friend who was hard-up who drove it for 2 more years, and hit a deer with it. It wasn't really phased, but I had to rig the mirror back on. I took it back when he was done and finally scrapped it for $200. It was still a fully working car when they took it away. 10/10, would buy again.

engagement ring :) better than my bitcoin investment...

My 1 year Krav Maga membership, a self defence system. Went from heavy smoker, no-cardio-at-all-person to feeling confident because I know how to defend myself, picked up running, swimming and regular body weight exercise on the side. Looking and feeling pretty good nowadays. More energy, brain activity, focus. Defo most bang for the buck.

Technically it was around $1800 but bought in two $900 lots, but my first 5000 shares in a promising mining company. Bought in at $0.33, sold at $1.12 two days before the CEO got caught being rather naughty and the whole thing tanked.

Monetarily, not massive returns, but as a percentage that was by far my biggest return on any investment.

Saving in a savings account at DCU - Digital Federal Credit Union. They give 5.1% interest rate for the first $1000

Risk free investment:-)

I guess it was quite a good investment to adopt my dog. But I think by now it cost me over $1000 so it does not qualify anymore.

This question is actually quite hard because so many things cost <=$1000, but it is hard to pick one that is the best.

10 shares of $GOOG in 2004.