There's no restriction on GPU esp. value based, budget based or mainstream based GPUs. Most older motherboards can support new GPUs w/o any issues. You need good PSU and CPU.
If you're buying GTX 1060/1070 then the pentium chip might be a bottleneck, otherwise GT series is GPU on a budget and is slower than GTX 1050.
You can manage it. GT 1030 is good card. You might look at radeons based on Polaris arch. rx 460. Have you checked for any offers for AMD RX550 because AMD gives pretty sweet deal on christmas.