Based on the photo in the question, it looks like a Manfrotto RC2 plate or third-party clone will fit it. The most basic RC2 plate is the Manfrotto 200PL-14. It's sometimes listed as a 200PL.
There are also many generic plates made by other manufacturers that fit the manfrotto RC2 receiver.
Cheap tripods typically use compatible quick-release plates. Search for "universal tripod quick release" on your favorite online shopping or auction site.
If the "universal" plate doesn't fit, you're unlikely to find one that's the right size. The tripods are too cheap for the manufacturers to sell custom-fitted plates separately. The scheme appears to ...