You can buy a cheap rack for just over $300(Atlas/Titan from Amazon), a serviceable barbell for $130 (Cap OB-86B, Amazon), and a couple hundred pounds of used iron plates on Craigslist (Craigslist). A good enough bench for about $100 (Adidas "Dumbbell bench" with 600 lb capacity also Amazon), but for ~$200 you can get a better one from Rogue. Do you need to build a platform, or are you just going to put down a horse stall mat or two ($40 each at Tractor supply)?
Or, you can go all Rogue and spend around double that for better equipment and better service across the board.
You're looking at this from the wrong direction, in my opinion. Set your budget, take the first $250/$300 and get a decent barbell, prioritize rack and bench quality after that, and plates last, since used ones work just as well as brand new.