Can I ask what benefits you thought having a SmartThings Hub would get you? Particularly since budget is a consideration.
The main benefit of a smartthings hub is that You can use Z wave and zigbee devices. But there are now many Wi-Fi devices available generally at lower cost. As well as devices which use their own proprietary networks like Wyze.
Wyze sensors, for example, work just fine with Amazon echo, but they don’t have any integration with smartthings at the present time. It’s not impossible to create some partial integrations If you use echo as a “ Man in the middle“, but then there’s no reason to have a smartthings hub.
So I’m just trying to figure out what your use would be for the hub to begin with. 
(There have also been some recent issues with Canadian residents being unable to get warranty service on SmartThings branded devices, including the hub. It’s very odd and very frustrating since people are being rejected even for hubs bought at major retailers like Staples and Amazon. So at the moment I am very nervous about suggesting that Canadian residents purchase smartthings branded devices. 
Canadian owner - confused, frustrated and, honestly, furious)
So I would suggest that initially you stick with an echo-based system and look at TP Link Kasa and Meross brands, along with Wyze for cameras and sensors, because you can’t beat the Wyze prices. 
Then if you have a specific use case which can’t be solved by those, you can come back and ask here about what other options might be.
If you like the smartthings app, you can use it for free without having a smartthings hub. As I mentioned, there’s no official integration with the Wyze sensors. But both TPLink and meRoss have smartthings integrations for some models. Again, no hub required.