How much can you afford? I'm still pretty inexperienced in this hobby, but my attitude has taken a 180 on this issue just recently. My first bulk order was this past Christmas... a case of .22lr. I was like: "Ohhhh, 5000 rounds?! Where will I store it all? Will my house explode? Does this mean I'm a gun nut?" When my big order arrived... I had a good laugh. As you probably know, a case of .22lr is no bigger than a shoe box!
Now, I equate ordering bulk ammo with getting a large package of paper towels at Costco. I know I'll eventually use it up... if I keep it in a dry area, it won't go bad... why wouldn't I buy in bulk to get the best per unit price and pocket the long-term savings? So now, I can't imagine having less than 6-8K+ rounds of .22lr on hand... and as my most frequently used caliber, I'd actually prefer to have 10k+ in stock. It also seems - dare I say? - prudent to buy well-priced bulk ammo right now in light of current events (rising national anti-2A sentiment, rising metal costs, our zealot Governor and his (unknown) bag of future anti-2A tricks, etc.). So, either shop around aggressively for best-priced ammo... OR, as @T Bill just suggested, if you use larger calibers, invest in reloading gear. (I do think you should try it first though... I get the sense people either love or hate reloading).