I replace a lot of carbs for customers.
I've found it is best not to buy the CHEAPEST one, but maybe the one that is a few notches up from the cheapest. I've installed many of the really cheap ones only to have the jets not be properly drilled out and the engine runs like garbage. It isn't a big problem with Briggs and Honda carbs, but Tecumsehs seem really sensitive to minor adjustments and any problems with a new carburetor will cause issues.
Luckily with Tecumsehs there is usually a wide variety to pick from on eBay, so I pick the $20 dollar carb instead of the $8 one. Judging by the pictures you can also tell if everything is really cheap. For me, the extra couple bucks is negligible, and means less time the machine is sitting in my garage half apart since I don't usually have to send them back.