I'll 2nd the cheap ebay carb try-out. I bought one for my bike recently b/c I just gave up trying to fix the original 39mm PWK (this carb is the definition of worn-out).
The flea-bay carb has been working pretty well (been about a month). Jury's out, I know they typically have low long-term durability. But, it let me at least ride the bike and sort out some other stuff with it... verify some things are 'ok' (bike doesn't overheat after new rads put on, brakes overhaul verified to work, etc...) so it's been worth the 30'ish bucks for that alone.
I doubt I'll pop for a Lectron, but I'd like to get a real PWK in the future when funds allow.