My solution was to purchase some card sleeves. I got 500 Max Protection clear board game sleeves (size 93mm x 62mm) from Comic Store West.
These puppies fit like a glove! I've dealt with a lot of card sleeves that split down the seam or have irregular cuts (sometimes cut larger or smaller than the specs) but every one of these was high quality. I was also worried that they'd be too thick or too slippery but they weren't either of those things! I was really impressed, especially for the price! I got all 500 for less than $10! To me, that's a no-brainer investment to protect my precious Dominion!
Thanks for the hook-up, Comic Store West!