what about dumbbell handles?
I got 2/$40 off amazon. I just load them up with 5s,10s,and 25s. They aren't as compact as the Hex dumbbells. And If you want to load them up past like 60 lbs it starts to get cumbersome, they are good for curls/tricep extensions, and single arm rows, but they are awful for farmer walks, and press variations. This is unless you have a large amount of 5/10 lb plates, which allow for more compact weight due to their reduced diameter when compared to 25s, 35s, and 45s.
I would suggest starting with the handles and loading them with plates which can be used on a barbell as well. I would invest in a big dumbbell set down the road.
I bought my barbell plates off of craigslist, and I believe I got 450 lbs for $210, and I had to haggle with the guy to get it down to that price, and they are lower end plates (Chinese, not York or Barbell).
In MN, I find guys on craigslist who have a connection with a distributor. The distributor sells large amounts of equipment that they acquire from gyms that either close or upgrade their equipment. They're usually easy to spot, they have multiple listings on craigslist of large pieces, or amounts of equipment.