The "easiest" thing to do is to use a microcontroller with a built-in TFT LCD controller in whatever the rest of the application is. This type of RGB interface is pretty common and supported by many processors; most families of medium-large micros should include some models with such a controller.
If you need a framebuffer, that's a fair bit of memory; if packed to 24bpp 768KB, or if aligned to 32bpp it would be 1MB, and you might want to double buffer, so you can double the memory requirement. If you can get away with an 8-bit LUT it's a bit more reasonable, but still quite a lot onboard a micro; might need external memory.
Another option would be a dedicated display controller that has a more 'usual' interface like SPI, but are still more or less just giving you access to a framebuffer - you need to do all the graphics primitives yourself. e.g. Epson S1D13700, which has a pretty cheap Arduino shield available. I don't think there are too many alternatives you can actually buy these days, most are using an embedded controller or a module using a bare die controller.
You'll need a tad bit more information from the supplier though, at the very minimum the timing specifications so you know how fast you can run it (though I guess you could trial & error it).
