These are the boost clocks of the cards correct of different brands?
Not sure which exact models of the same card you're looking at, but the difference of 90mhz will have a small effect on gaming performance depending on the architecture. Probably around 4-6fps difference, so in my opinion that $40 extra isnt worth it.
Also something to note, is that usually factory overclocks on cards like this, mean that you could yourself manually overclock your card easily without any hassle. Since usually brands like to make sure their cards are 100% stable so that means most GTX 950's should be able to reach the same clocks.
So in my opinion, go with the cheaper card (as long as the cooler is just as good) and just clock it up anyways to match...