Just my opinion here: If I was on a tight budget I wouldn't build that, I would go the used route and grab a sandybridge i5 cpu any decent-ish lga1155 motherboard to go along with it. It will be a better fit for your 780 i think, fewer bottlenecks and an overall more balanced system.
For the psu any reputable brand should be ok, I personally like seasonic, corsair, and silverstone. The more expensive models can be quieter and more efficient and maybe they will last a bit longer, but don't worry about getting a basic one as long as it's from a reputable brand, you should be ok.