You have tried the inexpensive items. To prevent acidic moisture corrosion, you need high-quality stainless steel products. This corrosion is a byproduct of high efficiency. High efficiency appliances remove heat to produce that higher efficiency; when the vent gases fall below dew point, they corrode. Plastic products were meant for that purpose, but were found to have cracking problems in cold climates.
Below is a list of manufacturers and suppliers of stainless venting products and competitors.