Investing in Mining Hardware vs Buying

Thoughts here?

Thinking about snagging an Nvidia GTX 30×0 to bump my current, moderate 22.40 MH/s hash rate, but I'm not entirely clear if the money would be better spent on directly purchasing Ravencoin while it's still relatively inexpensive, or on a beefy video card that could generate coins for the foreseeable future.

I'm not sure what to expect if a ton of ETH miners show up and the difficulty goes way up — will my GPU suddenly not be very effective at earning coins? Will I end up far behind where I would have been had I just purchased coins?

I know there is no one answer, but just curious what other people's stance on this is.