so...

Dustwallow has the WORST scale drop that i've found. I spent 2 hours farming Heavy Leather (for Thorium Brotherhood rep turn ins, and since I knew I could get scales as well) and after literally filling my inventory with stacks of heavy leather (like 140 hvy and a couple stacks of thick) I only had ALMOST one stack of scales.

Tanaris Turtles drop tons more scales than Dustwallow, they are low 40s, and drop more Thick Leather than Heavy Leather.

Hinterlands Turtles drop the most turtle scales hands-down. They also drop Thick Leather and Rugged leather like CRAZY. (In addition, I got golden pearls, and 2 nice BOE blues worth over 70g each, in one night!)

FYI, trash loots off turtles: Tails aren't worth selling if you are farming, the speckled scales are worth almost half a gold per stack though! Turtle meat sells well in AH to people ranking cooking skill (more often than you think, raw food is hard to buy!) All turtles drop the same greys regardless of level, and I've made *LOTS* of money selling speckled scales in steamwheedle or hinterlands FP town while I farm leather! Dustwallow turtles almost never drop clams, so if you hate opening clams, this is a bonus, but their leather is worse than the others.

Finally, the turtle recipes take dozens of scales per item. Scales are often in the AH for only a gold or two for a stack, but you will rarely see a HUGE amount of them, so be prepared to farm turtles till your eyes bleed..

where can i find turtlescales? i've killed turtles of all kind by the dozen but didn't find any scales...

So doing all of the wild leather quests you will need something like this:

114 thick leather
112 turtle scales
22 silken thread
12 heavy silken thread
2 cured thick hides
11 wildvines

correct me if im wrong.

Is doing this quest going to stop me from doing dragonscale leatherworking?

I've gotten turtle scales from the duskwallow marsh turtles near theramore on the east coast, and from the port/beach on the east coast of tanaris. They also tend to drop zesty clam meat if you need it for the cooking quest"clamette surprise"