Suggestions for budget video cards for Cycles Render on Linux

I’m an occasional blender user and I’ve been using it to produce fly-through models of installations that I am building. I’ve recently started using Cycles Render and realise I need a better graphics card as the CPU (Intel® Core™ i7-2600K CPU @ 3.40GHz) is doing a better job than the GPU of an old GeForce GT 52. I run Linux and CUDA is installed and integrated properly with Blender.

The images I’m rendering take about 20min for each frame with the CPU and longer with the GPU of the GeForce.

Money is very tight (and the exchange rate terrible), but I wonder if any can offer advice on a card that will speed thing up? The power supply of my computer is 500W. I’d like to keep my spending under R$800 (Brazilian Real) if possible. The cheapest online site for cards I believe is this one:

If anyone has time to look, there’s a filter at the top of the page. Some translations: “mais procurados” = most sought after, “preço crescente” = from low price to high, “preço decrescente” = high to low.

Within my budget and in the GeForce line, I’ve found:

GTX 750 Ti 2GB

Geforce GTX 950 2GB

Are these likely to get me out of trouble?

Thanks a lot!