The cost is higher, there's no doubt about that...you can make a $8 quart of paint last through many projects, whereas a can of decent spray paint will run you about $3 a can. I offset this by priming with brush primer (unless it's a super intricate piece-then I'll use spray primer) and then following with a few coats of the $0.99/can cheap stuff before applying my final color. On my kitchen chairs, I was able to get away with 1 can each of primer, flat black, and Krylon Oil Rubbed Bronze (tip: Walmart carries this brand, and it's cheaper than at Home Depot at $2.67/can).
I've finally found a solution to the second problem: the cramping. When you spray paint as much as I do, it's like boot camp for your hands. Even with switching hands (which can make for interesting results!), my index fingers get sore. The higher quality paint usually has a better trigger, but if you paint long enough you'll still end up with the claw. Enter the simplest little make-life-easier tool ever invented for the rattle can, The Spray Grip by Rustoleum
For less than $3, you can turn any can of spray paint into a spray gun- improving control and virtually eliminating hand cramping. You just slide it on the can and squeeze the trigger. I used it to paint my kitchen chairs, and WOW what a difference. I highly recommend this to anyone who loves to spray paint. I found mine in Walmart with the paint, but I'm sure any place that carries the rattle cans will also have this genius invention! Happy (claw free) painting!