You can build your own hardware with options in the docs here
https://meshtastic.org/docs/hardware/
I have enough projects going as it is, so I bought a prebuilt option. I feel it’s very reasonably priced 
https://store.rokland.com/products/wismesh-pocket
I’m still new, it’s a bit of a rabbit hole but very cool tech. The Meshtastic docs are pretty good, just take your time reading through it can be overwhelming