Since I was in NY this past weekend, I decided to visit the NY flower mart, and mock up a DIY bouquet to determine if 1) it's doable, 2) if it's cost effective.
Result: 1) It's definitely doable took me 1/2h 2) Not sure about the cost effectiveness... (The hydrangeas are 5.99 for 3 stems... for some reason cheaper than whole foods, costco, and fifty flowers; the lisianthus was 12.50 a bunch, but much cheaper if you buy bulk through fifty flowers; the wax flowers was 10 a bunch, again cheaper if you buy bulk through fifty flowers... however, I ended up with enough lisianthus/wax flower for maybe 1-2 more bouquet... so I'm not sure if bulk flowers would be cost effective as it's probably more than I'll need... I'll have to see if I can order through a local florist)